At a certain paint store forest green is made by mixing 4 parts blue paint with 3 parts yellow paint.Verdant green is made by mixing 4 parts yellow paint with 3 parts blue paint.How many liters of yellow paint must be added to 21 liters of forest green to change it to Verdant green?
Answers
A) 1/3
B) 7
C) 1/2
D) 1/7
E) 1/8
21 liter of Forset green have 12 liter of blue and 9 liter of yellow   Suppose we add x liter of yellow to make it a verdant green so the ratio of blue to yellow in verdant green is ¾ so the equation is   7lue/yellow =12/(9+x) = ¾   27+3x=48 =&gt; x =7   Answer : 7
<result>B</result>
At a certain paint store forest green is made by mixing 4 parts blue paint with 3 parts yellow paint.Verdant green is made by mixing 4 parts yellow paint with 3 parts blue paint.How many liters of yellow paint must be added to 21 liters of forest green to change it to Verdant green?