Its a multiplication by -3 on each term, so I think you're gonna answer is by r=-3, maybe?
First off, let's convert the percentages to decimal format, so our 77% turns to 77/100 or 0.77, and our 55% turns to 55/100 or 0.55 and so on
now, the sum of both salines, must add up to the 77% mixture, let's say is "y"
so, 11 + 4 = y, and whatever the concentration level is, must also sum up to the mixture's concentration of 77%
anyway thus

solve for "x"
There needs to be values to answer the question.
-3(x+(3))^2-4 is the answer