Answer: he saved $15
Explanation:
The regular price is $5.00 per rose bush, but last week they were on sale at 2 for $8.50. This means that the amount that one would cost is
8.5/2 = $4.25
If Jim bought 20 rose bushes last week, it means that the amount that he paid for 20 rose bushes is
20 × 4.25 = $85
The regular price is $5.00 per rose bush. If he had bought at the regular price, the amount that he would have paid is
5 × 20 = $100
Therefore, the amount saved by the bushes on sale is
100 - 85 = $15