What is 30% of 40?
30% = 0.3
so:
0.3 * 40 = 12
_________________________
Lou's class has 12 students in it. 8 of the students ran a race last weekend. What percent ran the race?
8 out of 12 ran so:
8/12 = 2/3
2/3 = 0.6667
0.6667 as a percentage:
0.6667 * 100 = 66.667%
[if you need it rounded to two decimal places: 66.67%]