Here's my step-by-step explanation:
Whenever you see the phrase "a number" in a word problem like this, they want you to make that mysterious number into a variable.
Let's write it out:
4 more than 3 times a number = 91
4 adds to (3 times n) = 91
4 + 3n = 91
Great, now it's just solving for n now.
3n = 91 - 4
3n = 87
n = 29
Hope this helps!
