Решите систему, x+y=5 и 7x+4y=640

Question

Решите систему, x+y=5 и 7x+4y=640

Answer 1

X+y=5
7x+4y=640

x=5-y
7(5-y)+4y=640

x=5-y
35-7y+4y=640

x=5-y
-3y=640-35

x=5-y
-3y=605

x=5-y
y=-201 2/3

x=5+201 2/3
y=-201 2/3

x=206 2/3
y=-201 2/3