need to set up and solve equation

Question

need to set it up the equation and solve it

a chemical company makes 2 brans of antifreeze.  the 1st brand is 35% pure antifreeze, and the 2nd brand is 55% pure antifreeze.  In order to obtain 60 gallons of mixture that contains 40% pure antifreeze, how many gallons of each brand of antifeeze must be used?

Answer 1

a represents the amount of 35%

 

0.35a + 0.55(60 - a) = 0.40(60)

 

Can you solve for a and answer?