Question

x+2y=70 and 2x+y=90 elimination

Answer 1

multiply eq. 1 by 2
2x+4y=140
2x+y=90
subtract
3y=50
y=50/3
x=70-2y=70-50/3=210-50/3= 160/3
x=160/3

Answer 2

x+2y=70 --------(1)

2x+y=90 ------------(2)

Multiply 2 on both sides in equation (1)

2(x+2y)=2(70)
2x+4y=140 ------------(3)

(3)-(2)

2x+4y=140
2x+ y = 90
-----------------
3y=50

y=50/3

Put y=50/3 in (1)

x+2y=70
x+2(50/3)=70
x+100/3 = 70
3x+100=70*3
3x=210-100
3x=110
x=110/3

Hope it helps