How do i find this answer?

Question

A store sells used DVDs for $8 each and used videotapes for $6 each. The function rule 8d + 6v can be used to represent the total selling price of DVDs d and videotapes v. Then use the function rule to find the price of 5 DVDs and 3 videotapes.

Answer 1

Hi Livi,

 

They tell you that the function rule can give you the total price, which makes sense because you are already given the individual prices. Now the question is telling you that there is a different amount of DVDs and videotapes, so now we have to look at the function rule and see how they got that.

 

One DVD costs $8. Two DVDs would cost 2 * $8. From this pattern, d DVDs should cost 8 * d, which is in the function rule. The same goes for videotapes, where each videotape costs $6 and the number of videotapes can be represented by v. 

 

Now we can answer the question, since we know the pattern. To find the price of 5 DVDs and 3 videotapes, we can use the function rule, where d is now 5 and v is now 3.

 

8 * d + 6 * v

 

8 * 5 + 6  * 3

 

40 + 18 = $58

 

Hope this helps!