Random Math Equation for an int

Im trying to make something to where it creates random math to equal to a variable. For example

sNum = 10
# Do something here
fNum = 3 * 2 - 3 + 7
fNum = sNum
True

I've tried thinking on ways to do this with no luck yet so I want to see if anyone has done something similar or can just think faster

Constraints: Only *, +, -, /
It can be any amount of numbers in the equation as long as its over 4 and under 10

Any help?