Question

5.How much pure antifreeze must be added to 12 gallons of 10% antifreeze to make a 40% antifreeze solution?

Answer 1

anti@1 = 12(.10-.40)/(1-.40) ; just disregard the negative sign maybe

Answer 2

I got 6 :) but check it

Answer 3

6 + 12(.10) =? 18(.40)

6 + 1.2 =? 7.2 ; looks good