How to solve (equation) with 5 / 1 x-4 / 1 x = 40

How to solve (equation) with 5 / 1 x-4 / 1 x = 40

1) Is it 5 / x-4 / x = 40? Is x the denominator?
That's two times X
5-4=40x
x=1/40
2) If the equation is wrong, it's 1 / 5x-1 / 4x = 40
So multiply both sides by 20, 4x-5x = 800
x=-800
3) If it's 5 / 1 times x-4 / 1 times x = 40
That's 5x-4x = x = 40

X-5 / 1 x = 40 to solve the equation

X-5 / 1 x = 40
4x/5=40
x=40*5/4
x=50

40% x + 1 / 2 x = 90 to solve the equation
30% of a number is equal to one fifth of 45. What's the number ten? (solve by equation)

40% x + 1 / 2 x = 90
0.4x0.5x=90
0.9x=90
x=90/0.9
x=100

How to solve the equation of 1.5x + 19.8 = 10.8

1.5x=-9.x=-6