Answer:
3x + 15 = 34.
Explanation:
Whenever an expression states "the sum," that means that there is going to be addition in the problem. So, now that we know that, we can take the numbers out of the statement and figure out their places of where they belong.
When a statement in math says "some number," it means that there is a variable. A variable is a letter that represents a mystery number that could be anything in the situation. So, for this situation we will use x, one of the most common variables used in math. When you have a number in front of a variable, that means that you are multiplying the number by the mystery number: the variable. So far we have:
3x + ? = ?
Now, we add the 15 into the expression. Because it says the "sum" of 3x and "15," we will be adding the two. Also, the word "is" basically means "equal to" in math. So, now we can put the whole equation together to get:
3x + 15 = 34.
(If you need me to solve it, I can do that too.)
I hope this helps.