How many gallons of a 10% antifreeze solution and a 25 % Antifreeze solution must be mixed to make 3 gallons of a 20 % antifreeze solution? Solve with equations

How many gallons of a 10% antifreeze solution: 0.10x 
and a 25 % Antifreeze solution must be mixed: 0.25y 
to make 3 gallons of a 20 % antifreeze solution: (3)(0.20)=0.6 

but x+y=3 (so y=3-x) 
and we write 


0.1x+0.25(3-x)=0.6 
which gives us x=1 gallon 



:)