8a - 4b = 20
5a - 8b = 62
Multiply the first equation by (-2):
-16a + 8b = -40
5a - 8b = 62
Sum the equations:
-16a + 5a + 8b - 8b = -40 + 62
- 11a = 22
a = 22 / -11
a = -2
Since 5a - 8b = 62 and a = -2, then:
5 * (-2) - 8b = 62
-10 - 8b = 62
-8b = 62 + 10
-8b = 72
b = 72 / -8
b = -9
