First solution:

Let’s rewrite the problem in the form of a proportion: if 30 is 100%, then 150 is x. Step 1: Write the proportion: =
Step 2: Multiply both sides by 150:
=
Step 3: Simplify the equation by reducing fractions: 5*100% = x
Step 4: Conduct multiplication on the left side: 500% = x

Second solution:

Multiply the answers by 30. The correct answer should result in 150. For instance,
5%*30 = 150% = 1.5 150 – answer A is wrong, 500%*30 = 15,000% = 150 – answer E is right.

Third solution:

150 is greater than 30, so the right answer should exceed 100%. 200% of 30 is 2 times more than 30, thus
200%*30 = 6,000% = 60 150
and answer D is wrong. So, only answer E remains and it has to be the right choice.

Pitfalls:

Read the question carefully and do not miss “percent” (answer key A is wrong). Also the order of the numbers matters (answer B is wrong)

Useful formulas:

Percentage