The sum of a number and 15

x + 15

Step-by-step 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