A chemist mixes some 70% solution with
some 40% solution to obtain 120 gallons of
50% solution. Find the number of gallons of
each solution.
I've stated the variables which is x= the number of gallons for 70% and y= the number of gallons for 40%.

Question

A chemist mixes some 70% solution with 
some 40% solution to obtain 120 gallons of 
50% solution. Find the number of gallons of 
each solution.
I've stated the variables which is x= the number of gallons for 70% and y= the number of gallons for 40%.

aum · Answer

"x" gallons of 70% solution is mixed with "y" gallons of 40% solution to form 120 gallons of 50% solution.
x + y = 120  ----- (1)
0.7x + 0.4y = 120*0.5 = 60   ----- (2)

Solve for x and y.