SOLUTION: Pedro is making brown paint by mixing 4 parts green paint with 5 parts red paint. He wants to make 36 gallons of brown paint. How many gallons of red paint will Pedro need?

Algebra ->  Customizable Word Problem Solvers  -> Numbers -> SOLUTION: Pedro is making brown paint by mixing 4 parts green paint with 5 parts red paint. He wants to make 36 gallons of brown paint. How many gallons of red paint will Pedro need?      Log On

Ad: Over 600 Algebra Word Problems at edhelper.com


   



Question 235962: Pedro is making brown paint by mixing 4 parts green paint with 5 parts red paint. He wants to make 36 gallons of brown paint. How many gallons of red paint will Pedro need?
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let r = gallons of red paint needed
Let g = gallons of green paint needed
given:
(1)r+%2B+g+=+36
(2)r%2Fg+=+4%2F5
----------------
From (2)
(2)5r+=+4g
(2)5r+-+4g+=+0
Multiply both sides of (1) by 4
and add (2) to (1)
(1)4r+%2B+4g+=+144
(2)5r+-+4g+=+0
9r+=+144
r+=+16
and, since
(1)r+%2B+g+=+36
16+%2B+g+=+36
g+=+20
16 gallons of red and 20 gallons of green are needed