Answer:
28
Step-by-step explanation:
You divide 21 by 3 and then add it again!
21 is 75% of 28.
75/100 × x = 21
Multiplying both sides by 100 and dividing both sides by 75,
we have x = 21 × 100/75
x = 28
If you are using a calculator, simply enter 21×100÷75, which will give you the correct answer as well.