Question

If x - 2y = 1 and 2x - y = -4, then x + y = ?

Answer 1

x + y = -5

Explanation:

x - 2y = 1

2x - y = - 4

then:

x = 1 + 2y

then:

2(1+2y) - y = -4

(2*1 + 2*2y) - y = -4

2 + 4y - y = -4

3y = -4 -2

3y = -6

y = -6/3

y = -2

x = 1 + 2y

x = 1 + 2*-2

x = 1 - 4

x = -3

Check:

x - 2y = 1

-3 -2*-2 = 1

-3 + 4 = 1

Answer:

x + y = -3 -2= -5