Question

1. Calcula a si a/b = 5/20 y a-b = -3.
2. Calcula b si a/b = 2/3 y a+b = 15.

Answer 1

a/b = 5/20
20a = 5b
4a = b

a - b = - 3
a - 4a = - 3
- 3a = - 3
a = 1
----------------------------
a/b = 2/3
3a = 2b
3a/2 = b

a + b = 15
a + 3a/2 = 15
(2a + 3a)/2 = 15
5a/2 = 15
5a = 30
a = 6

3a/2 = b
3(6)/2 = b
18/2 = b
9 = b