Precalculus, Chapter 7, 7.3, Section 7.3, Problem 24

(1/5)x+(1/2)y=-13
x+y=-35
Multiply first equation by 2,
(2x)/5+y=-26
Subtract the above equation from the second equation,
(x-(2x)/5)=-35-(-26)
(5x-2x)/5=-35+26
(3x)/5=-9
x=(-9)*5/3
x=-15
Plug in the value of x in the second equation,
-15+y=-35
y=-35+15
y=-20
Solutions of the equations are x=-15 and y=-20