Answer: 18
Step-by-step explanation:
Evaluate 7 r − 15 /s
Given that r = 3 and s = 5
7r - 15/s
Substitute 3 for r and 5 for s in the above expression
7(3) - 15/5
= 21 - 3
= 18
Answer:

Step-by-step explanation:
Let x = number of books that Hannah donated
We know that the number of students is 150 and the total number of books is represented by b, we can write that as:
Average number of books donated by each student = 
Now we know that Hannah donated 3 times as much as the average. We can write that as:

4800in.=400ft.
I hope this will help