Answer:
x + 15
Explanation:
The problem is in word form. Write the problem in algebraic form, which means using numbers and symbols (like + - ÷ x).
Take the key word:
'sum' - This means the answer when you add numbers. To add you use the + plus sign.
The sum of a number and 15 means adding a number and 15.
There is no equal sign because the question does not say "equals" or "is".
Choose a variable to represent "a number". I will choose the letter 'x'. Add 15 to 'x'.
x + 15