The temperature rose so you add the amount it rose to the starting temperature
68.7 + 9 = 77.7 degrees
It then dropped so mow you subtract t the amount it dropped:
77.7 - 12.3 = 65.4 degrees
The answer is 65.4 degrees
According to google, the red marks mean those two lines are the same length. If that's the case, we know that x is the angle in both corners of the lower triangle. We also know that because the angle of a straight line is 180, that the top angle of the bottom triangle is 140, because it's divided into two parts, one of which is 40. That leaves 140 for the rest. Now we know that there are 180 degrees in a triangle so x=(180-140)/2 = x=20degrees.
The right angle in the left corner is 90 degrees. It is divided in two parts, the lower one of which we just found to be 20. So the other part must by 70deg.
So for the upper angle y, we have 180-70-40= y=70degrees
