Question 1063672
Divide members of the first equation by 9.
Divide members of the second equation by 2.


{{{system(x+y=1,y=7x+10)}}}


Arrange the two equations into the same form.
{{{system(x+y=1,7x-y=-10)}}}


You can eliminate y this way:
{{{x+y+7x-y=1-10}}}
{{{8x=-9}}}
{{{highlight(x=-9/8)}}}


You could use substitution to find y.