Total monthly budget: $2100+800+650+400+550=4500$. Combined work hours per week: $40+40=80$. Using $4$ weeks per month gives $80\times 4=320$ hours per month. Required hourly wage (each, at the same rate): $4500\div 320=14.0625\approx$ $14.06$. Higher Austin housing costs raise the needed wage compared with some cities.

Sales tax is applied to the purchase subtotal. Compute the tax: $45.60 \times 0.0825 = 3.762 \approx 3.76$ dollars. Then add it to the subtotal: $45.60 + 3.76 = 49.36$ dollars total.

Compute savings on a 60-dollar purchase of three 20-dollar items:

• Store A: 25% of 60 dollars is $0.25 \times 60 = 15$ dollars saved.
• Store B: Buy 2, get 1 free means you pay for only 2 items: save 20 dollars.
• Store C: 10 dollars off over 40 dollars is 10 dollars saved.
• Store D: 30% off one item is $0.30 \times 20 = 6$ dollars saved. The greatest savings is 20 dollars at Store B. Decision factors: Buy-2-get-1-free works best when you buy in multiples of three; percent-off applies even if you buy fewer or more items.

Simple interest uses $I = prt$. Here $I = 1200 \times 0.035 \times 4 = 168$ dollars. Compound interest (for comparison) uses $A = p(1+r)^t$: $A = 1200(1.035)^4 \approx 1377.03$, so compound interest earned $\approx 177.03$ dollars. Simple interest is on principal only, while compound interest earns interest on interest, so compound grows faster over time. Knowing this helps you choose savings accounts that can grow your money more effectively.

First find weekly earnings: $12.50 \times 25 = 312.50$ dollars. Income tax is a percent of earnings: $312.50 \times 0.15 = 46.875 \approx 46.88$ dollars. Do not subtract unless asked for take-home pay.

Needed hours: $4200\div 15=280$ hours per month (combined for the household). If two adults worked $40$ hours per week each, that would be $80\times 4=320$ hours per month, which would cover the Dallas budget at this rate. Different cities' costs change the hours needed at a given wage.

Regular total is $2 \times 80 = 160$ dollars.

• A: Save $0.30 \times 80 = 24$ dollars.
• B: Save 40% on one item: $0.40 \times 80 = 32$ dollars saved.
• C: Save $0.10 \times 160 = 16$ dollars now, plus rebates: $2 \times 10 = 20$ dollars later; total savings 36 dollars.
• D: Qualifies for 20 dollars off; save 20 dollars. Greatest savings is Option C (36 dollars). Decision factors: rebates reduce your net cost but arrive later and require submission; percent-off applies immediately; check rebate limits.

Simple interest: $I = prt = 2000 \times 0.04 \times 5 = 400$ dollars, so final $= 2400$. Compound interest: $A = p(1+r)^t = 2000(1.04)^5 \approx 2433.31$, so interest $\approx 433.31$ dollars. Difference $\approx 433.31 - 400 = 33.31$ dollars in favor of compound. Simple interest is on principal only; compound earns interest on interest, so it grows faster—useful when comparing savings and investment accounts.

Base merchandise total: $3 \times 18 = 54$ dollars.

• P3: Add a 6-dollar item to reach 60 dollars pre-discount ⇒ free shipping. Discount 12 dollars ⇒ total $60 - 12 = 48$ dollars, shipping 0 ⇒ 48 dollars total.
• P1: 20% off 54 is $0.20 \times 54 = 10.80$ saved ⇒ $54 - 10.80 = 43.20$ dollars; add 8 shipping ⇒ 51.20 dollars total.
• P2: Free shipping only ⇒ 54 dollars total.
• P4: 15% off 54 is $0.15 \times 54 = 8.10$ saved ⇒ $54 - 8.10 = 45.90$ dollars; shipping 4 ⇒ 49.90 dollars total. Lowest total is 48 dollars with P3. Decision factors: thresholds are usually based on pre-discount totals; adding a small item can unlock a better discount and free shipping if the net drops more than the filler's cost.

Sales tax is the purchase subtotal times the tax rate: $59.99 \times 0.0775 = 4.649225 \approx 4.65$ dollars. The question asks for the tax amount, not the total price.