The answer is 35000. Because 2 significant figures means the 2nd number, in this case it is the number 4 and if we want to round off something, look at the next number, if more than 5 or 5, you must round up.
2x + 5 = 3x - 45 [alternate interior angles]
3x - 2x = 5 + 45
x = 50
4y - 1 + 2x + 5 = 180 [supplementaly angles]
4y + 2(50) + 4 = 180
4y + 100 = 176
4y = 76
y = 19
20 because when you divide 12 by 3/5 you get 20 use a calculator