Answer:
x=y and y=-8
Explanation:
Multiply the second equation by -1
(9x-10y=17)
-1(-10x-10y=10)
Becomes:
-9x-10y=17
10x+10y=-10
Add equations together to eliminate y:
x=7
Then solve x=7 for x:
x=7
Then plug in x to the original equation:
-9x-10y=17
Substitute 7 for x in -9x-10y=17:
(-9)(7) - 10y = 17
-10y - 63 = 17
-10y -63 + 63 = 17 + 63 (add 63 to both sides)
-10y = 80
-10y/-10 = 80/-10 (divide both sides by -10)
y = -8