well, in short, the students and chaperones are at a 2 : 9 ratio, and we know there are 171 students, how many chaperones then, so long they maintain a 2:9 ratio?

It’s not going to be C because 10 is already in the question
I think it would be $77.00
One
The sum of two rational numbers is always rational. sqrt(9) + sqrt(25) = 3 + 5 which is rational. sqrt(16/100) = 4/10 = 2/5 is also rational. 3/28 is rational as well.
Two
Those are irrational. sqrt(10) + pi = ???? You cannot reduce this to any kind of fraction. Two irrationals always give a rational.
Three
The irrational number controls the answer. 10 + sqrt(5) is irrational. The 10 is OK. It is raional, but sqrt(5) is not a rational number.
<u>Answer:</u>
37 minutes
<u>Step-by-step explanation:</u>
Lena has 20 dollars. 20 - 12.23 = 7.77
Lena has $7.77 dollars left.
We divide this by .21 to see how many minutes her call was.
7.77 ÷ .21 = 37
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