Question 1189865
 A certain brand of house paint must be purchased either in quarts at $12 each or in gallons at $18 each.
 A painter needs a 3-gallon mixture of the paint consisting of 3 parts blue and 2 parts white.
 What is the least amount of money needed to purchase sufficient quantities of the two colors to make the mixture?
:
3 gal = 12 qts
let b = amt of blue paint in quarts
let w = amt of white
:
b + w = 12
and using the ratio of blue to white
{{{b/w}}} = {{{3/2}}}
2b = 3w
b = (3w)/2
b = 1.5w
find in terms of w
1.5w + w = 12
2.5w = 12
w = 12/2.5
w = 4.8 quarts of white required
then
b = 12 - 4.8 = 7.2 quarts of blue
subtract no. of whole gallons from each, cost 2 *18 = $36 
.8qts of white and 3.2 qts of blue close enough to 4, get another gal of blue
that would now be 3 * 18 = $54 plus 1 qt of white, 54 + 12 = $66
: 
Summarize $66: 2 gal of blue ($36), 1 gal and 1 qt of white, ($18 + $12)