subs don't work properly

I'm try to replace a symbolic variable at my expression. Example at image below

I'm want to get x*0.375, but (3*x)/8 isn't equal. Maybe I'm doing something wrong?

[Azzi Abdelmalek]

Instead of posting a picture, it's easier for you and for us, if you copy and paste your code.

Answer 1

[Azzi Abdelmalek]

syms  x a
expr=x*a
acounted=3/8
subs(expr,a,3/8)

3/8=0.3750,

Why do you think 3/8 and 0.3750 are not equal?

[NIkolay Ermakov]

Oh, maybe I'm really wrong. Sorry.