How many gallons of 70% antifreeze solution must be mixed with 90 gallons of 30% antifreeze to get a mixture that is 60% antifreeze

Answer 1

0.7 X + 90*0.3 = 0.6 ( X+ 90)

0.7 X + 27 = 0.6 x + 54

0.1X + 27 = 54

0.1X = 27

X = 270