The general governing equation here is y = k*x.
Find the constant of proportionality, k, by subbing 10 and 25 for x and y, respectively: 25 = k(10). Then k = 25/10, or 5/2.
The governing equation is now y = (5/2)x.
Evaluate this for x = 8: y = (5/2)(8) = 20 (answer)
