Sat 2015 Practice Test #1 Answer Explanations

Choice B is correct.
To determine the number of salads sold, write 
and solve a system of two equations. Let 
[
equal the number of 
salads sold and let 
y
equal the number of drinks sold. Since a total 
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+ 
y
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the total revenue from selling 
[
salads and 
y
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---

WKHHTXDWLRQ[
y
PXVWDOVRKROG7KHHTXDWLRQ
[
+ 
y
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+ 2
y
= 418, and subtracting (2
[
+ 2
y
) 
from the left-hand side and subtracting 418 from the right-hand side 
RI[
y
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_
salads sold, 
[
, was 
[
= 
Choices A, C, and D are incorrect and could result from errors in writing 
the equations and solving the system of equations. For example, choice C 
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WRWDOSULFHRIDVDODGDQGDGULQNDQGWKHQURXQGLQJXS
QUESTION 20 
Choice D is correct.
Let 
[
be the original price of the computer, in 
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[ơ[ [
is the discounted price, in dollars. The sales tax is 
SHUFHQWRIWKHGLVFRXQWHGSULFHVR[
) represents the sales tax 
Alma paid. The price 
S
, in dollars, that Alma paid the cashiers is the 
sum of the discounted price and the tax: 
S [[
) which 
can be rewritten as 
S [
). Therefore, the original price, 
[
, of 
S
_
the computer, in dollars, can be written as
in terms of 
S
.
Choices A, B, and C are incorrect. The expression in choice A 
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REWDLQHGE\VXEWUDFWLQJWKHGLVFRXQWRIIURPWKHRULJLQDOSULFHDQG
DGGLQJWKHVDOHVWD[RI+RZHYHUWKLVLVLQFRUUHFWEHFDXVHRIWKH
tax is over the discounted price, not the original one. The expression in 
choice B is the result of adding the factors associated with the discount 
DQGVDOHVWD[DQGUDWKHUWKDQPXOWLSO\LQJWKHP7KHH[SUHVVLRQ
in choice C results from assigning 
S
to represent the original price of 
the laptop, rather than to the amount Alma paid to the cashier. 
QUESTION 21