Question 18
It is known that Annie can wash 3 plates every minute, while Betty can wash 2 plates every minute. Also, it is known that Annie can wash 9 cups every minute, while Betty can wash 7 cups every minute. If there are a total of 134 dirty plates and cups and both of them worked together in washing all the dirty plates and cups and finished in exactly 20 minutes, how many dirty plates are there?