Question

Find x and y
2x - 5y = -70
-5x+10y : 100​

Answer 1

By formula method,

-5 70 2 5

10 -100 -5 -10

x/500-700= y/-350+200= 1/-20+25

x/ -200= y/-150=1/5

x= -40 y= -30

Answer 2

2x-5y+70=0-----1 ×5

-5x+10y-100=0------------- ×2

10x-15y=-140=0――――1

-10x+20y=200=0------2

eliminating eqn 1and 2

10x-15y=-140

-10x+20y=+200

____+___-_____

0+35y =60

y=60/35

y=12/7

putting y=12/7 in eqn1

10x-15(12/7)=-140

10x-180/7=-140

10x=(140×7+7) (180/7)

10x=-980+180/7

10x=-800

x=800/10 x=-80