Question

the sum of 14 and a number is equal to 17

Answer 1

I assume that the question is: what is this nunber?

we write this like this:

The sum of 14 and a number  is 14+x

we know that this equals 17, so: 14+x=17.

Let's substract 14 from both sides:

x=17-14

x=3

so the number is 3.

Answer 2

Sum = +

14 + n = 17

n+14=17

Subtract 14 from both sides.

n+14−14=17−14

n=3