3x - 3y = -12 ------------- (1)
7x + 2y = -19 --------------(2)
(1) x 2 : 6x - 6y = - 24 ----------- (1a)
(2) x 3 : 21x + 6y = -57 ----------- (2a)
(1a) + (2a) : 27x = - 81
x = - 3
Sub x = -3 into (1) : 3(-3) - 3y = - 12
y = - 12 + 9
y = - 3
Answer( -3, -3)
If you draw a simple diagram you can see that point to form a right angle ACB, C must be at (3,0).
When you multiply you add the exponents, so 7^9*7^-3=7^6
