.
b + h = 14, (1)
= 20. (2)
Transform:
b = 14 - h, (1')
b*h = 40. (2')
Substitute (1') into (2')). You will get
(14-h)*h) = 40,
14h - h^2 = 40,
h^2 - 14h + 40 = 0,
Factor left side:
(h-10)*(h-4) = 0.
There are two solutions:
1) h = 10. Then b = 4.
2) h = 4. Then b = 10.
Answer. There are two solutions: 1) h = 10, b = 4 and 2) h = 4, b = 10.
Solved.