Answer: There are 138 plates that are to be washed by her if she started at 7:15 and end at 7:38, and the function will be f(x)=6x.
Explanation:
Since we have given that
She washed 30 plates from 7:30 to 7:35 ,
That means in 5 minutes , number of plates get washed by her = 30
We need to find the number of plates from 7:15 to 7:38
First we count the number of minutes

In 1 minute, number of plates get washed by her is given by

In 23 minutes, number of plates get washed by her is given by

Equation to represent how many plates Ana has left to wash at a particular time after her start at 7:15 is given by

Hence, there are 138 plates that are to be washed by her if she started at 7:15 and end at 7:38, and the function will be f(x)=6x.