how to use substitution for 4x+3y=13 and x+y=4

A) 4x + 3y = 13  B) x + y = 4 B) x = 4 -y Then we substitute this into Equation A A) 4 (4-y) + 3y = 13 A) 16 -4y +3y = 13 A) -y = -3 y = 3 x = 1