To buy 20 DVDs at the given rate, it would cost $200.
In the given chart, the total cost of purchasing DVDs is directly proportional to the number of DVDs purchased.
Each DVD costs $10, so to find the total cost of buying 20 DVDs, we can multiply the cost of 1 DVD by 20.
The calculation would be:
Total Cost = Cost per DVD x Number of DVDs
Total Cost = $10 x 20 = $200
So, it would cost $200 to buy 20 DVDs at this rate.
The probable question may be:
The chart shows the number of DVDs a person can purchase and the total cost.
| Number of DVDs | Total Cost |
| 1 | $10 |
| 2 | $20 |
| 3 | $30 |
| ... | ... |
| 20 | $200 |
At this rate, how much would it cost to buy 20 DVDs?