Solving for 'y'
2x - 2y + 5 = 0
Add 2y on both sides
2x + 5 = 2y
Divide by 2 on both sides
y = x + 5/2
y = x + 2.5
Solving for 'x'
2x - 2y + 5 = 0
Subtract 2x on both sides.
-2y + 5 = -2x
Divide 2x on both sides
x = y - 5/2
x = y - 2.5
The answer is C, t-19=-12. This is because the temperature decreased from t by 19 degrees and ended up at -12 degrees. Hope this helped!