Question

A housepainter buys 40 gallon-size cans of paint for $920. Some of these are blue paint that cost $30 per gallon and the rest are white paint that cost $20 per gallon.
How many gallons of white paint does the painter buy?

Answer 1

Answer:

28 gallons

Step-by-step explanation:

Let the amount of white paint be x.

Then, the amount of blue paint = 40 - x

A.T.Q.

20x + 30(40-x) = 920

20x + 1200 - 30x = 920

10x = 280

x = 28

Hope it helps.

Answer 2

Answer:

$x + y = 40$

$30x + 20y = 920$

$x + y = 40$

$30x + 30y = 1200$

$30x + 30y - 30x - 20y = 1200 - 920$

$y = 28$

$he \: buys \: 28 \: white \: gallons$