Answer:
The number is 100.
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.