Question

x + y = 4; 2x + 5y = 1 solve by elimination by substitution

Answer 1

x+y=4
x=4-y
2x+5y=1
2(4-y)+5y=1
8-2y+5y=1
3y=-7
y=-7/3
x-7/3=4
x=19/3

Answer 2

x+y=4
2x+5y=1
5x+5y=20
2x+5y=1
- - -
3x=19
x=19/3
y=4-19/3
y=12-19/3
y=-7/3