Answer:
C. 
Step-by-step explanation:
Since 40% of the students prefer chocolate ice cream, 60% don't prefer chocolate ice cream. Use this proportion set equal to 25 to find the number of students who prefer vanilla ice cream, instead of chocolate ice cream.
Answer:
9
Step-by-step explanation:
we know by definition that

so now we evaluate

and if we want to do an extra step

which works.
Answer:
Step-by-step explanation:
Let the number of ounces of
A = x
B = y
A scientist has two solutions, which she has labeled Solution A and Solution Each contains salt. She knows that Solution A is 40% salt and Solution B is 55% salt. She wants to obtain 90 ounces of a mixture that is 45% salt. How many ounces of each solution should she use?
Our system of equations is given as
x + y = 90.... Equation 1
x = 90 - y
40% × x + 55% × y = 45% × 90 ounces
0.4x + 0.55y = 40.5....Equation 2
We substitute 90 - y for x in Equation 2