Answered

3 times a number x,subtracted from 18 is less than -90

Verified Answer :

In mathematical expression, we can write it as:
18 - 3x < -90

Subtract 18 from both sides, 
-3x < -108
Cut the minus sign, 
3x < 108
Divide both sides, by 3
x < 36

In short, Number is smaller than 36

Hope this helps!