Answer:
the answer is the second one 480ft^3
B-a=0.
Starting from the original equation,
a+b=2a
We can isolate b by subtracting a from both sides:
a+b-a=2a-a
b=a
Substituting this into b-a, we have
a-a = 0
There are 1,16,280 different recital programs possible.
Given: A pianist plans to play 4 pieces at a recital from her repertoire of 20 pieces and is carefully considering which song to play first, second, etc.
It means the repetition of pieces is not allowed.
When repetition is not allowed, then the number of ways to arrange n things where r things taken together is given by:-

Now, the number of different recital programs are:-

Hence, there are 1,16,280 different recital programs possible.
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Answer:
B
Step-by-step explanation:
Complementary angles are 2 angles that add up to 90 degrees.
If the first angle is 72 degrees, then subtract 90 - 72 to get the measure of the second angle.
90 - 72 = 18
= 18 degrees