I got 16.8 , but she’ll need roughly 17 gallons of paint :)
how i did it :
1. so you know she’ll need 4/5 per book case, and there are 16 bookcases. 2. So you do 16 x 5, then you get 84 3. and you divide 84 by 5. and you’ll get 16.8, that’s how many gallons of paint she needs
Solve it by substitution. First let's rewrite the first equation (3x+4y=16) so we have y = something, then we'll substitue that in to the other equation. 3x+4y=16 4y=-3x+16 y=-3/4x+4
Now we can substitute this into the other equation.
(1073 + 1108 + x) / 3 = 1000 (2181 + x) / 3 = 1000 ....multiply both sides by 3 2181 + x = 1000 * 3 2181 + x = 3000 x = 3000 - 2181 x = 819 <== they would need to earn $ 819 on Sunday
