x+y+3=0

2x+y+8=0

Solution: x=-5 y=2

If two straight lines are perpendicular, the product (k) of their slopes is equal to-1.

2x+y- 10 = 0 k=-2

K= 1//2 of the straight line to be found.

Let the equation be y =1/2x+b.

Bring in (-5,2)

Get b=9/2.

Get the linear equation: x-2y+9=0.