Answer:
91 campers can swim
Explanation:
step 1
Find the number of campers
we know that
The ratio of counselors to campers at a camp is 1 : 9
so
by proportion
Find the number of campers if there are 13 counselors
Let
x-----> the number of campers
1/9=13/x
x=9*13=117 campers
step 2
How many campers can swim?
we know that
The ratio of campers who can swim to campers who cannot swim is 7 : 2
so
The ratio of total campers to campers who can swim is 9 : 7
by proportion
Find how many campers can swim for a total of 117 campers
Let
x----> the number of campers that can swim
9/7=117/x
x=117*7/9
x=91 campers can swim