The difference of 9/10 of a number and 30 is the same as 3/5 of the number. Find the number.

The number is 100.

Step-by-step explanation:

In order to find the number that is hidden in the given problem, there are a series of equivalencies that have to be made to create an equation to solve the problem.

9/10 = 0.9

3/5 = 6/10 = 0.6

So, this equivalencies established, we are going to perform the following calculation to find the number, by using an equation:

0.9X - 30 = 0.6X

0.9X = 0.6 X + 30

0.9X - 0.6X = 30

0.3X = 30

X = 30 / 0.3

X = 100

According to this calculation, the number is 100.