Work. Do Not Solve

Multiple Choice

work. Do not solve.
-5x + 9y = -12
-4x - 4y = -32
A) Substitution B) Addition
Answer: B
Write the word or phrase that best completes each statement or answers the question.
-In a chemistry class, 9 liters of a 4%-saline solution must be mixed with a 10% solution to get a 6% solution. How many liters of the 10% solution are needed?

A) 3.5 L
B) 4.5 L
C) 5.5 L
D) 9.0 L