Answer
Find out the how many laps did Beth swim and write expression the total number of laps Beth swam .
To proof
As given
Beth swam laps to raise money for a charity.
Beth raised $15 plus $0.65 per lap that she swam.
She raised a total of $80.00
Let x represent the number of laps Beth swam.
Than the expression becomes
15 + 0.65× x = 80 .00
Simplify
15 + 0.65x = 80
0.65x = 80 -15
0.65x = 65

x = 100
Therefore the number of laps did Beth swim be 100 .
Hence proved