Can anyone solve this im not sure how to ???

How many litres of pure antifreeze must be added to 77 litres of a 20​% antifreeze solution to obtain a 60​% antifreeze​ solution?

1 Answer
Dec 1, 2017

231 L


We can put it into fractions is that’s easier

So #(77L) / (20%) = (xL)/(60%)#

X represents the unknown L of solution.

So there’s two ways of doing this:

1) To get 60% from 20%, you would need to multiply that by 3

So #((77L)*3)/((20%)*3)=(231L)/(60%)#, and therefore x = 231 L


2) Cross multiply to solve for x


#4620 = 20x# (I removed the units for better visual)

You want to isolate x, so divide both sides by 20 to get:

#4620/20 = 20x/20#

#231 = x #

So in the end, there would be 231 L of pure antifreeze to get 60% solution