40% of what number is 84?

210

Step-by-step explanation:

When working out a percentage for example 20% of 40, I follow 2 simple rules to get to the answer.

⇒ Multiply the percentage by the other number

⇒ Divide the multiplied number by 100

So for the example, Find 20% of 40

⇒ Multiply the percentage by the other number

→ 20 × 40 = 800

⇒ Divide the multiplied number by 100

→ 800 ÷ 100 = 8

So 20% of 40 is 8.

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Using the method above we can set up an equation. We will call the number we want to find 'x'

⇒ Form the equation

→    

⇒ Multiply both sides by 100 to isolate  

→    

⇒ Divide both sides by 40 to isolate x

→    

So we know that 40% of 210 is 84. We can use the method at the top to see if our solution is correct

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⇒ Multiply the percentage by the other number

⇒ Divide the multiplied number by 100

So, Find 40% of 210

⇒ Multiply the percentage by the other number

→ 40 × 210 = 8400

⇒ Divide the multiplied number by 100

→ 8400 ÷ 100 = 84

So 40% of 210 is 84.

i think the answer is b