7.If 16x − 2 = 30, what is the value of 8x − 4 ?
A) 12
B) 15
C) 16
D) 28Master SAT Math
Acing the math section all
comes down to strategy,
including ones like Read
the Full Question (RTFQ).
For more strategies and
tips, check out the videos
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Premium Portal.Here’s How to Crack It
First, see if you can eliminate answers by Ballparking, which can also work on algebra questions. To go
from 16x to 8x, you would just divide by 2. Dividing 30 by 2 gives you 15, so 28 is way too big.
Eliminate it. The correct answer is not likely to be 15, either, because that ignores the –2 and the –4 in the
question.
To solve this one, add 2 to each side of the equation to get 16x = 32. Divide both sides by 2, which gives
you 8x = 16. But don’t stop there! The full question asks for 8x − 4, so (C) is a trap answer. You have to
take the last step and subtract 4 from both sides to find that 8x − 4 = 12, which is (A).
One Piece at a Time
When dealing with complicated math problems, make sure to take it one little piece at a time. We call this
strategy “bite-sized pieces.” If you try to do more than one step at a time, especially if you do it in your
head, you are likely to make mistakes or fall for trap answers. After each step, see if you can eliminate
any answer choices.
Let’s give it a try.
9.A paper airplane is thrown from the top of a hill and travels horizontally at 9 feet per
second. If the plane descends 1 foot for every 3 feet travelled horizontally, how many feet
has the plane descended after 5 seconds of travel?
A) 3
B) 10