Kylie had 50 boards. She used some, represented by the variable $u$, and has 5 left. We need to find the equation that represents this situation.

1. Problem Description

Kylie had 50 boards. She used some, represented by the variable $u$, and has 5 left. We need to find the equation that represents this situation.

2. Solution Steps

The total number of boards Kylie had is

5

0. She used $u$ boards, and after using them, she had 5 boards left. This means the initial number of boards minus the number of boards used equals the number of boards left. Therefore, the equation should be:

$50 - u = 5$

We can check this with an example. Suppose Kylie used 45 boards. Then $u=45$. So the equation would be $50 - 45 = 5$, which is true. The other option is $50 \div u = 5$. If that were true, then $u = 50 \div 5 = 10$. So $50 \div 10 = 5$, which is true, but the problem statement says that Kylie had 5 boards left over.

3. Final Answer

$50 - u = 5$