Possible solution follows. First, write a system of equations for this problem:
x = 4y
Next, substitute and solve the quadratic equation for y:
(4y+5)(y+5)= 4y2+20y+5y+25= 4y2+25y+25=91
Note: you can solve this using quadratic equation solver http://examn8.com/QuadraticEquations.aspx
There are two different solutions: y1=2 and y2=-8.25. Correspondingly, x1=8 and x2=-33, thus two pairs of numbers satisfy the criteria: [8,2] and [-33,-8.25]
Hope this may help.