2. 5 is 25% of what number?

10

Step-by-step explanation:

25% is 25 over 100 = 1 over 4 of a number (% means "out of 100")

Setting the number as x means x * 1 over 4 = 2.5

To find x we will divide both sides by 1 over 4, which is also multiplying by 4

2.5 * 4 = 10