Question

solve by the method of (1) elimination (2) Substitution



10x -9y=12
3x -9y =17​

Answer 1

Step-by-step explanation:

elimination

10x-9y=12

-(3x-9y=17) (subtract the equations)

=>7x= - 5

●x= -5/7

3x-9y=17

-15/7-9y=17

-9y=17+15/7

-9y=119+15/7

-63y=134

●y= -134/63

substitution

10x-9y=12

10x=12+9y

x=12+9y/10

=>3x-9y=17

3×12+9y/10-9y=17

36+27y/10-9y=17

36+27y-90y/10=17

36-63y=170

-63y=170-36

-63y=134

●y= -134/63

3x-9×-134/63=17

3x+(134/7)=17

(21x+134)/7=17

21x+134=119

21x=119-134

21x= -15

x= -15/21

●x= -5/7