We have

First, we can combine like terms 3y and -7y to get -4y.
Then, we have

We could then subtract 8 on both sides to get

Finally, we isolate y completely by dividing both sides by -4, to get
Answer:
Total cost = Cost per month × 12 months per year × Number of years
= $21 × 12 × 8
= $2,016
Step-by-step explanation:
Some examples of multiples of 2/5 are 4/10, 6/15, 8/20, 10/25, 12/30, and 14/35.