4x + 7y = 47
7y = -4x + 47
y = (-4/7)x + 47/7
5x - 4y = -5
-4y = -5x - 5
y = (5/4)x + 5/4
-(4/7)x + 47/7 = (5/4)x + 5/4
(-4/7 - 5/4)x + 47/7 = 5/4
(-16/28 - 35/28)x + 47/7 = 5/4
(-51/28)x + 47/7 = 5/4
(-51/28)x = 5/4 - 47/7
(-51/28)x = 35/28 - 188/28
(-51/28)x = -153/28
-51x = -153
x = 3
4(3) + 7y = 47
12 + 7y = 47
7y = 35
y = 5
(3,5)