Answer: 
Step-by-step explanation:
By definition, a relation is a function if and only if each input value has one and only one output value.
For this exercise it is important to remember that thw "Input values" are the values of the variable "x"and the "Output values" are the values of the variable"y".
In this case you have the following function provided in the exercise:

Then, to solve this exercise, you need to follow these steps:
Step 1. You have to substitute
into the function given.
Step 2. Finally, you must evaluate in order to find the corresponding output value (or the value of the variable "y")
You get that this is:

Answer: 5
hrs
<u>Explanation:</u>
Jasper:
per hr
Yolanda:
per hr
Together:
per hr
Jasper + Yolanda = Together
+
= 
+
= 
3x + 21 = 7x
21 = 4x
= x

Answer:
This question doesn't really make sense...
Step-by-step explanation:
Please try to correct it.
I hope this helped, have a nice day