A. If you draw the graphs you will find that B, C and D are all false.
If we break the answer down, we can solve this pretty easily.
We can represent Dic's age with x.
Tom's age is 5 MORE (+5) than TWICE (2x) Dic's age (x)
Therefore, our answer is 5+2x (Five more than twice Dic's age)
The correct answer is C: 5+2x
A + c = 824 represents number of tickets to sell
20a + 12c = 13,344 represents cost of each type of ticket
multiply equation 1 by -12 to cancel the variable 'c' and solve for 'a'
-12(a + c = 824)
-12a - 12c = - 9888
20a + 12c = 13,344 add equations together
-----------------------------
8a = 3456 divide both sides by 8
a = 432
To find children's tickets substitute adult numbers back into equation 1.
a + c = 824
432 + c = 824
subtract 432 from both sides
c = 392
adult 432, children 392
In other words, find the inverse of the given function f(x).
1. Replace f(x) with "y." y = 8(x+10)
2. Interchange x and y: x = 8(y+10)
3. Solve this for y: y+10 = x/8, or y = x/8 - 10
-1
4. Replace "y" with "f (x) "
-1 x-80
f (x) = ---------- (Answer)
8
