F(x) = 2x + 1
To find the inverse of a function you just need to switch the x by y or vice-versa:
-> y = 2x + 1
-> x = 2y + 1
After that you isolate the y again:
-> 2y = x - 1
-> y = (x-1)/2
-> f^-1 (x) = (x-1)/2
Answer:
9/10 is the answer. 7/8 is 70/80 and 9/10 is 72/80
The game costs 25 dollars. If 6/5 = 30 then 5/5 would be 25