# SAT practice Test 3

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#### If three times a number is equal to that number minus 7, what is the number?

Correct! Wrong!

Let "a number" be x. Three times this is 3x. This is equal to x-7 (3x=x-7). Add a -x to isolate the number. This leaves you with 2x=-7. Divide by 2, and you're left with x=-3.5.

#### >The amount of skin samples that David needs for an experiment must be greater than 11 but less than or equal to 27. Which of the following represents an acceptable range for David's experiment?

Correct! Wrong!

Simply jot down the inequalities as they are presented in the word problem and match up to the answer selection. That leaves Answer 3.

#### If 2x+2y=0, which of the following must be equivalent to 2x-2y?

Correct! Wrong!

STEP ONE. Separate the two variables and get rid of the 0 (2x=-2y).
STEP TWO. Divide by 2 (x=-y).
STEP THREE. Plug in -y for x and solve. This leaves Answer 1.

#### Which of the following is equivalent to 4x2-4x-48?

Correct! Wrong!

STEP ONE. Pull out your four to simplify the equation.
STEP TWO. Solve for the two resulting equations. Answer 2 is the correct choice.

#### If 2a+3b=26 and 5a+4b=51, what is the value of a+b?

Correct! Wrong!

STEP ONE. Add the two equations (7a+7b=77).
STEP TWO. Divide by 7 (a+b=11). Answer 4 is the correct choice.

#### If x2+4xy+y2=-44 and y-x=14, which of the following could be the value of x?

Correct! Wrong!

Simple enough answer choices. Simply plug in the numbers into the simpler equation. This will help produce a potential answer for y as well. You can then check your answers in both equations to make sure they "fit."

#### If three times a number (x) is equal to that number plus six, what is five times that number plus 20 minus that number?

Correct! Wrong!

A careful reading of the word problem will leave you with the following: 3x=x+6, 5x+20-x
3x=x+6
DIVIDE by 2 x=3
5x+20-x=32
SIMPLIFY x 4x+20

Correct! Wrong!