Question

X - Y = 11 2x + Y = 19 where do the lines cross

Answer 1

Just solve the equations:
A) X - Y = 11
B) 2x + Y = 19
Multiply A) by -2

A) -2X  +2Y = -22 then add to B)
B) 2x + Y = 19
3Y = -3
Y=-1

A) X - -1 = 11
x = 10