a. Find the total area to be painted. b. Each quart of paint costs \( \$ 8 \) and covers 90 square feet. Find the cost to paint this wall once. Justify your answer.

To find the total area to be painted, start by determining the dimensions of the wall. If the wall is, for example, 10 feet tall and 15 feet wide, the area would be calculated as height multiplied by width: \(10 \text{ ft} \times 15 \text{ ft} = 150 \text{ square feet}\). Now, for the cost, first divide the total area by the coverage per quart of paint: \(150 \text{ sq ft} \div 90 \text{ sq ft/quart} = 1.67\) quarts needed. Since you can’t buy a fraction of a quart, round up to 2 quarts. Multiply by the cost: \(2 \text{ quarts} \times \$8/\text{quart} = \$16\). So, it will cost $16 to paint the wall once.