If x and y are positive numbers and the average of 4, 20 and x is
equal to the average of y and 16, then the ratio x: y is
The average of 4,20, and x is (24+x)/3
the average of y and 16 is (y+16)/2
but they are equal
so (24+x)/3 = (y+16)/2
solve, then form the fraction x/y