Adisk cost $3 more than a tape. rolex bought five disks and two tapes. the total cost was $120. what was the price of a disk?

First, I would organize your information into equations. So, the first sentence would be:

 d = 3 + t                 d = disk   and     t = tape

Second and third sentence would be the equation:

 5 d + 2 t = $120

To find the price of the disk, you would follow these steps.

5 (3 + t) + 2 t = 120            substitute d, with the equation that has a total, for 

                                           (3 + 2), then solve for t

15 + 5 t + 2 t = 120          distribute

15 + 7 t = 120                  add like terms

7 t = 105                         subtract from both sides

t = 15                               divide from both sides

Then you substitute 15 in the first equation.

d = 3 + t                           substitute

d = 3 + 15                        add

d = 18

So, d = 18 and t = 15. To check this, you just need to substitute the right variables.

1) 18 = 3 + 15

     18 = 18

2) 5 (18) + 2 (15) = 120

               90 + 30 = 120

                     120 = 120

When checking, we can see that the correct answer is $18 for the price of the disk.

$18

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