Aclass had 30 pupils at the beginning of this school term, but now has 5 more pupils. what is the percent of increase?

16.67%

Explanation:

You need to learn how to calculate percent to be able to perform this type of problems by yourself.

Percent is the ratio of a quantity on base to 100 parts.

In this case the increase is 5 students of an initial group of 30, so you need to find the equivalent expression with a base of 100 instead of 30.   That is, you need to find the ratio with denominator 100 equivalent to the ratio 5/30:

  x         5
=
100      30

=> x = (5 / 30) * 100 = 16.67%.

Also, you should notice that calculatind the percent is done dividing the parts by the whole and multiplying by 100, i.e. (5 / 30) * 100, which is the same done above.