Question

I write the equation for one-
fifth of x is 2
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Answer 1

Answer:

One fifth of a number is 2. What is 3 by 5 of this number?

Rosario Emerald

Answered 2 years ago

One fifth of a number is 2. What is 3 by 5 of this number?

To do this we will call the number we need to find x. We know that 1/5x=2. This means, that x=2*5. 2*5=10. x=10. So the question is now “What is 3 by 5 of 10?” If “by” means “divided by”, it would mean that it wants us to find 3/5 of 10. It cannot mean “multiplied by”, “subtracted/reduced by”, or “added/increased by” because those would give us one of the following: “What is 15 of 10”, “What is -2 of 10”, or “What is 8 of 10”. None of those make any sense. So, back to the question. What is 3/5 of 10. Well, translating this to an equation yields “3/5*10”. The way I like to do this sort of thing is to first convert both numbers to fractions. By doing this, we get 3/5*10/1. Now we just have to multiply the numerators together, and then multiply the denominators together. However, in this case we should do one more step. It is called “canceling”. To do this, we first must convert all numbers into their prime factorizations. 10 is the only composite number, so we will convert it. 10=2*5. We now see if the numerators of either fraction share prime factors with the denominator of the other fraction. 10 shares one factor with 5. That factor is 5. So we divided both 10 and 5 by 5. 10/5=2 and 5/5=1. We now get 3/1*2/1. This is the same as 2*3. 2*3=6. This means that 3/5*10=6.