Answer:
4x = 10 + 3x
Explanation:
Let's make "a number" into the variable x.
"Four times a number" means that we have 4 "times" x, which indicates multiplying 4 by x: 4 * x = 4x.
"is equal to" obviously can just be written as =.
"10 more than" means that we add 10 to something, so we have 10 + ____ .
"3 times the number" is similar to before with the 4 times a number: instead of 4, though, we have 3 this time. We multiply 3 by the number x: 3 * x = 3x.
"10 more than three times the number" would then be: 10 + 3x.
Now, put this all together: 4x = 10 + 3x
The mathematical expression is thus: 4x = 10 + 3x. (From here, you can solve for x, but since that wasn't the question, I'm leaving it as the unsimplified expression)
Hope that helps!