Решите систему y=-1.4x x-y=18

Question

Решите систему y=-1.4x x-y=18

Answer 1

 y=-1.4x
 y=-1.4*7.5
y=-10.5      

 x-y=18
x-(-1.4x)=18
 x+1.4x=18
 2.4x=18
x=18/2.4
x=7.5