Bony takes 2 hours to wash 500 dishes, and Farah takes 3 hours to wash 450 dishes. How long will they take working together to wash 1000 dishes?

A 1 hour

B 2 hours

C 2.5 hours

D 3 hours

Correct Answer: Option C

Ben washes 500 dishes / 2 hours = 250 dishes / 1 hour.

Frank washes 450 dishes / 3 hours = 150 dishes / 1 hour.

dishes that Frank washes in x hours + dishes that Ben washes in x hours = 1000 dishes

250x + 150x = 1000

400x = 1000

x = 2.5