Personal Financial Literacy>Calculating Sales Tax and Income Tax(TEKS.Math.7.13.A)

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.

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.

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.

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.

Total monthly budget: $1600+650+500+350+400=3500$. One worker's monthly hours: $40\times 4=160$. Required hourly wage: $3500\div 160=21.875\approx$ \$21.88$. Because San Antonio's costs are lower than some other Texas cities, the required wage is lower than it might be elsewhere.

Bank A (simple): $I = 1500 \times 0.03 \times 6 = 270$, final $= 1770$ dollars. Bank B (compound): $A = 1500(1.028)^6 \approx 1770.31$ dollars. Compound is slightly higher by about \$0.31$ dollars because compound interest adds interest on interest. Even small differences can matter over time when choosing accounts.

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.

Income tax is calculated from gross pay: $2{,}800 \times 0.12 = 336$ dollars withheld. Do not add this to the salary; it is the amount taken out.