Please help how do I solve each system by graphing?

Question

x+2y=4
x-y=1

Answer 1

x + 2y = 4
x - y = 1

Multiply top by -1

-x - 2y = -4
x - y = 1

-3y = -3
y = 1

x - y = 1
x - 1 = 1
x = 2

ANS : (2,1)

for a graph, go to www.quickmath.com, click on Plot under Equations, then click on Advanced.