Tomas bought 3 software apps and 2 e-books for a total of $21. The two e-books cost $12. If s represents the cost of each app, the total cost of all 5 items is represented by 3 s + 12 = 21. Which statement about verifying the solution for s is true?

s = 3

Step-by-step explanation:

First compute the cost of the three apps:

21-12=9

The cost of the three apps is $9 then.

Since s is the price of the apps, we deduce the equation:

3s=9

/3

s = 3

n=9

step-by-step explanation:

7 times a number = 7n

decreased by 13 = 7n-13

same as is =

5 times the number = 5n

increased by 5 = 5n+5

7n-13 = 5n+5

2n=18

n=9

18.75 gallons

step-by-step explanation: