Answer:
143
Step-by-step explanation:
lets make a fraction:
so
91 oil changes/7days
lets take "x" as the unknown # of oil changes:
so
x/11
91/7=x/11
we can cross multiply:
91*11=7*x
1001=7x
143=x
so 143 oil changes in 11 days
Hope this helps!
Answer: 
Step-by-step explanation:
Given
Propane produced heat energy of 
The volume of the tank is 
The energy produced by this propane tank is

Answer:
f ○ g(x) = x and g ○ f(x) = x is the correct composition
Step-by-step explanation:
INVERSE FUNCTIONS: Two functions are said to be inverse of each other if for every y = f(x), there exists a function g(x),
such that x =
= g(y)
Now, here if we need to show tha two functions f(x) and g(x) are inverse functions of each other , then show that for every x:
1. f o g(x) = f(g(x))= x
2. g o f(x) = g(f(x)) = x
If any two functions satisfy these two conditions, then they are inverse of each other.
Answer:
She did not qualify the exam.
Step-by-step explanation:
Given data
Total no of question in a test = 20
No. of question answered correctly = 16
Percentage of question answered correctly

But in order to get in the exam the student must have to score at least 90 %. But she got only 80 % so she did not qualify the exam.
Answer:
e = s×0.72
Step-by-step explanation:
we need to find how much does a 1 song costs
so, 2.16 ÷ 3 = 0.72 $