C. multiply because of the order of operations
6.25t + 8 = 12.5t + 13
Subtract 8 from both sides
6.25t = 12.5t +5
Subtract 12.5t from both sides
-6.25t = 5
Divide -6.25 by both sides
t = 0.8
Since you are given that the student registered early, the total number you deal with is all students who registered early.
211 + 329 = 540
number of undergraduates who registered early = 211
Among students who registered early:
p(undergraduate) = 211/540
8÷3 is 2.666666667, 6 is greater than 5 so rounded to the nearest tenth it is 2.7