Question

How do work this problem 1/10 of 90 is

Answer 1

When you see the would 'of' it generally means to multiply.
what you're going to do is take the one from the fraction $\frac{1}{10}$ and multiply 90 by it, which would equal 90. Then you take the 10 (the denominator) and divide 90 by it. So it will 1 × 90 and then 90 ÷ 10.  
So, you multiply by the numerator and then divide that answer by the denominator. Do you understand?

Answer 2

well if you divied 10 to 90 it equals 9 so 1/10 of 90 is 9. you just divide the number 10, and then you will get the answer. hope it helps :)