Solve the system of equations by substitution 9x5y 80 xy2Sol

Solve the system of equations by substitution. 9x+5y= -80 x-y=2

Solution

9x+5y= -80 ,

x-y=2 =>x=2+y

substitute x=2+y in 9x+5y= -80

9(2+y)+5y= -80

18+9y +5y =-80

18+14y=-80

14y=-80-18

14y=-98

y=-98/14

y=-7

we have x-y=2

x-(-7)=2

x+7=2

x=2-7

x=-5

so x=-5 , y=-7 is solution