Answer:
Paul has five counters.
Step-by-step explanation:
Paul has an unknown number of counters.
Paul has two less than seven counters.
Let's see the attached drawing. A total number of seven counters.
If we have two less than seven, it means that of the total seven counters, we have to delete two.
C = 7 -2 = 5
So, Paul should have five counters.If we delete the red boxes, we can see the five counters.
If f(X)= 7x +5/3 - x =6x +5/3
y= 6x +5/3
6x= y-5/3
f^-1(y)=x=(y-5/3)/6
So we can write
f(f^-1(y))= f((y-5/3)/6) = 6 (y-5/3)/6 +5/3= y-5/3+5/3= y
The same result can be obtained for f^-1(f(x))=x
If the function is f(x)= 7x +5/(3-x) then it is not invertible since it is not injective (pictures)
