Solve using substitution.

x + 3y = - 13

5x + 7y = - 9

From equation 1

x = - 3y-13

plug this into equation 2:-

5 (-3y-13) + 7y = - 9

-15y - 65 + 7y = - 9

-8y = 56

y = - 7

Now plug y = 7 into equation 1

x - 21 = - 13

x = - 13 + 21 = 8

solution is x = 8, y = - 7