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14. The correct answer is (C). To find the slope of a line express it in y = mx + b form, where m repre-
sents the slope.
A perpendicular line would have a slope that is the negative reciprocal of 
. The negative reciprocal is
15. The correct answer is (E). (73)
36
= 1.20122113364 E 67 or a similar expression depending on your
particular calculator. The calculator is using scientific notation to express a huge number.
1.2011 . . . 
× 10
67
means move the decimal point 67 places to the right, resulting in a 68 digit number.
16. The correct answer is (E). Here is a good problem on which to use one of our alternative strategies.
Test answer choices:
(A)
12 – 3 = 9
Wrong! Both expressions have the same sign.
15 – 3 = 12
(B)
12 – 4 = 8
Ditto!
15 – 4 = 11
(C)
12 – 11 = 1
Ditto!
15 – 11 = 4
(D)
12 – 12 = 0
Wrong! Both expressions are said to be nonzero.
15 – 12 = 3
(E)
12 – 13 = –1
Bingo!
15 – 13 = 2
But how do we prove mathematically that 13 is correct? We don’t have to. We eliminated four of the
choices, so the one that remains has to be the correct answer to the test question.

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Mathematics Level IC/IIC Subject Tests
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17. The correct answer is (B). Here you could use either of two approaches. First, you can attack the
problem by treating the equations as a system of simultaneous equations:
3m + n = 15
3n + m = 13
Use the first equation to solve for n:
n = 15 – 3m
Substitute this expression for n in the second equation:
3(15 – 3m) + m = 13
45 – 9m + m = 13
–8m + 45 = 13
8m = 32
m = 4
And find the value of n:
3(4) + n = 15
12 + n = 15
n = 3
As an alternative, you could test answer choices. Just substitute the values given for m and n until you
find a pair that satisfies both equations.