Final answer:
To earn more than $800 after paying for the lawn mower, Kaila and Joey need to mow more than 70 lawns.
Step-by-step explanation:
To represent the number of lawns Kaila and Joey need to mow to earn more than $800 after paying for the lawn mower, we can use the inequality: 15x - 250 > 800, where x is the number of lawns they need to mow.
To solve this inequality, we can add 250 to both sides to isolate the variable: 15x > 1050. Then, we divide both sides by 15: x > 70. So, they need to mow more than 70 lawns to earn more than $800 after paying for the lawn mower.
Therefore, the inequality to represent the number of lawns they need to mow is: x > 70.