Question

Substitution method

x-7y=-9
-x+8y=10

Answer 1

x = -2, y=1

Explanation:

x-7y=-9---------------------equation 1

-x+8y=10-------------------equation 2

From equation 1, make x the subject of formula

x=7y-9----------------------equation 3

substituting x=7y-9 in equation 2,

-(7y-9)+8y=10

Expanding bracket

-7y+9+8y=10

Collecting like terms

8y-7y=10-9

y=1

substituting y=1 in 3

x=7(1)-9

x=7-9

x=-2