Her average in first three test = 89
This means, her total scores in first three test were = 3 x 89 = 267
Her average in four tests = 91
This means, her total scores in four tests are = 364
267 give the sum of first three test scores. and 364 give the sum of scores with fourth test adding in three tests.
So, subtracting 267 from 364 will give us the scores of Fourth test.
Scores of Fourth test = 364 - 267 = 97
Thus, Samantha's Claim is correct
First, some defintions
reciprocals are like a/b and b/a or 5/1 and 1/5
remember,

john's fraction is reciprocal of sarah's
john=a/b
sarah=b/a
david multiplies his by sarah and gets 12/35
(b/a)(david)=12/35
multplies his number by john and gets 12/35
(a/b)(david)=15/7
hmmm
(b/a)(david)=12/35 and
(a/b)(david)=15/7
if we divide them then we do





square root both sides

therefor
b=2 and a=5
john's number is a/b=5/2
sarah's number is 2/5
david, hmm
sarah times david=12/35
2/5 times david=12/35
times both sides by 5/2
david=60/70
david=6/7
check other
john times david=15/7
5/2 times 6/7=15/7
30/14=15/7
15/7=15/7
true
sarah's favorite number is 2/5
john's favorite number is 5/2
david's favorite number is 6/7
There is some ambiguity here which could be removed by using parentheses. I'm going to assume that you actually meant:
x-3
h(x) = ---------------
(x^3-36x)
To determine the domain of this function, factor the denominator:
x^3 - 36x = x(x^2 - 36) = x(x-6)(x+6)
The given function h(x) is undefined when the denominator = 0, which happens at {-6, 0, 6}.
Thus, the domain is "the set of all real numbers not equal to -6, 0 or 6."
Symbolically, the domain is (-infinity, -6) ∪ (-6, 0) ∪ (0, 6) ∪ (6, +infinity).
The answer would be C) 2,300.