How to calculate that 5 out of 6 x divided by 1 out of 5 equals 40.5?

How to calculate that 5 out of 6 x divided by 1 out of 5 equals 40.5?

5x of 6 divided by 1 of 5 = 40.5
5x = 40.5 * 1 / 5
5x = 8.1
x=8.1*6/5
x=9.72

Similar to the solution equation of 5x-5 / 6 = 2 / 5, 4x-6 × 1 / 4 = 9 / 10, X × (1-15%) = 119!
If the title, urgent!

4x-6x1/4=9/10
4x-6/4=9/10
4x=9/10+6/4
4x=12/5
x=3/5

3x-1 / 12 = 2 / 15 4x * 3 / 5 = 9 / 10 4 / 5x-1 / 5x = 3 / 8 3 / 4x + 5 = 30

3x-1/12=2/15
De denominator: 180x-5 = 8
x=13/180
4x*3/5=9/10
To denominator: 40x * 6 = 9
x=3/80
4/5x-1/5x=3/8
To denominator: 32-8 = 15x
15x=24
x=8/5
3/4x+5=30
To denominator: 3 + 20x = 120x
100x=3
x=3/100