i usually use one of the following methods Carole;

1) 17.5 % of say 350

Divide 350 by 100 = 3.5 (move decimal point two places to left)

then multiply by 17.5

17.5 x 3.5 = 61.25

2) The 17.5% is a mixed numeral, so it can be changed to an improper fraction firstly.

This will give 35 / 200

35 / 200 x 350 / 1

Which will cancel down to;

35 / 4 x 7 / 1

35 x 7 = 245 / 4 = 61.25

3) Break it down the following way;

17.5% of 350

10% of 350 = 35

1% of 350 = 3.5

.5% of 350 = 1.75

10% = 35.

7% = 3.5 x 7 = 24.5

.5% = 1.75

Add 35 + 24.5 + 1.75 = 61.25