Solve by substitution:
2x-y = -5
-x+-y =10

{2x-y = -5 => -y=-5-2x    /*(-1)    y=2x+5
{-x+-y =10

Substitute y in the second equation:

-x-y=10

-x-(2x+5)=10

-x-2x-5=10

-3x-5=10    /+5

-3x=15     /:(-3)

x=-5

y=2x+5=2*(-5)+5=-10+5=-5

y=-5

Solution:   (-5; -5)

1. 22

2. 1

3. 7

4. 18

step-by-step explanation

e2020 got it right

see explanation

step-by-step explanation:

since the sequence is geometric there is a common ratio r between consecutive terms, that is

r = 4 ÷ - 2 = - 2

r = - 8 ÷ 4 = - 2

r = 16 ÷ 8 = - 2

the next term - 13 must be incorrect as it should be - 32 for the sequence to be geometric.

the first 4 terms are therefore geometric with common ratio r = - 2