This could mean two things from how you’ve written it.
It could mean there is an X with the denominator 4 or it could mean there’s an X with the denominator 4-7.
I am going to work with the first one and assume the 7 is separate. Apologies if that is incorrect.
First, I would add the 7 to both sides.
This leaves you with X/4 = 4
Then, multiply both sides by 4, to get X on its own.
This leaves X=16, which is the answer.
Answer:
10 liters of 40% solution
10 liters of 10% solution
