geometry math problem

Question

You are planning to paint a house.

a.

How many square feet will you need to​ paint? (There are four​ windows, each

9

feet by

2

​feet; two​ windows, each

1

feet by

10

​feet; and two​ doors, each

80

inches by

36

​inches, that do not require​ paint.)

b.

The paint that you have chosen is available in gallon cans only. Each can covers

100

square feet. If you want to use two coats of​ paint, how many cans will you need for the​ project?

c.

If the paint you have chosen sells for

​$21.36

per​ gallon, what will it cost to paint the​ house?

Answer 1

Let x = the number of square feet of the house, to be painted, including windows and doors' areas

112 = the area of the 6 windows and 2 doors; 9(2)(4) +(1)(10)(2) + (20/3)(3) = 72+20+20 = 112

Paint is needed for 2 coats = 2(x-112) = 2x-224 square feet

divide by 100 to get the number of cans needed

= x/50 -2.24 cans

round that up to the nearest integer

multiply by $21.36 to get the total cost

23.36(2x -2.24) = at least 46.72x - 52.3264 dollars to paint the house, exact amount depends on how far up the required rounding to nearest integer