Rounding off to the Nearest hundred is giving a number which ends as 5600 or 6700 etc. To round a number to its nearest hundred you have to first look at the tenths place ( in this case 53) if a number is 50 or above you round it to the next hundred example - 5678 rounded to the nearest hundred is 5700. If a number is below 50 example - 1348, you round it to the same hundred - 1300.
Since the slope of the line is (31/4 - 25/4) / (5/4 - 3/4) = 3 that means that for every 1 that x increases, y increases by 3 so an example could be 1 3/4 for x and 9 1/4 for y.
