According to the given data we have the following system of equations:
7x+5y=-7
9x-2y= -9
x?
y?
In order to calculate both x and y we would have to make the following calculation:
7x+5y=-7
7x=-7-5y
x=(-7-5y)/7
x=-1-5y/7
So, we gonna subsitue the value x=-1-5y/7 in the equation 7x+5y=-7 as follows: