Question

Tina and Renee are teachers who decided to grade their exams together. They had 200 exams to grade. Tina can grade 20 exams per hour and Renee can grade 15 exams per hour. If they work together, how long will it take for them to finish grading the exams?

Answer 1

5
`(3)/(7)` hours

Explanation:

let t = time

20t + 15t = 200

t(35) = 200

t =
`(200)/(35)` =
`(40)/(7)` = 5
`(3)/(7)`