Answer:
7n
Step-by-step explanation:
x = -5
y = 4
3x + 4y = 1 /*(-4)
4x + 5y = 0 /*3
---------------------
-12x - 16y = -4
12x + 15y = 0 +
-y = -4
12x = -15y
12x = -60
3/52