<h2>
Answer:</h2>
The equation is given by:

<h2>
Step-by-step explanation:</h2>
Let the number be denoted by x.
Now, we are given a word phrase as follows:
One-third of a number less than nine is equal to seven.
Now this word phrase could be mathematically expressed as a equation by:
one-third of x is: 1/3 x
and this number less than 9 is given by:

Now, this number is equal to 7.
i.e. we finally have:
