Hi Lania!
If Koby can work 22 math problems in 30 minutes, then he can work 44 in an hour (multiply your problems completed and time elapsed by 2).
Now, we have to figure out how many he can complete in 3 hours, so all we have to do is multiply our current math problems by 3.
44 * 3 = 132
This means that Koby can complete D.) 132 math problems in 3 hours.
I hope this helps!
Answer: 
Step-by-step explanation:
You need to analize the information given in the exercise.
In this case you know that the List price is:

And, based on the data given, you also know that the Trade discount is:

Then, the first step you need to apply is to multiply the List price by the Trade discount, as you can observe below:

Now it is important to remember that, by definition, the Net cost can be found by subtracting the List price (which in this case is $74.13) and the product of the List price and the Trade discount (which in this case is $24.71).
Then, through this procedure, you get the following Net cost:

To make this easier the answer is, "y = 2x + 5"
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