Question

Solve the following system of linear equations by addition:
8x-9y=1
1.6x-1.6y=16

Answer 1

We have the equations-

8x-9y=1 -1st eq
1.6x-1.6y=16 -2nd eq

Dividing the second equation throughout by -1.6 we have -

-x+y=-10 -3rd eq

Now multiply the 3rd eq by 8, we have
-8x+8y=-80 -4th eq

Now add the 4th and 1st equations,

8x -9y=1
-8x+8y=-80

Therefore -8x and +8x get cancelled and we have,

-y=-79
Therefore y=79 and since -x+y=-10
substituting the value we have-

-x +79=-10
Therefore x=-89

Answer,
x=-89, y=79 !!!!