Nicole and Chelsea each improved their yards by planting daylilies and ornamental grass. They bought their supplies from the same store. Nicole spent $9 on 1 day-lily and 2 bunches of ornamental grass. Chelsea spent $39 on 5 daylilies and 8 bunches of ornamental grass. Find the cost of one day-lily and the cost of one bunch of ornamental grass.

 1) D

2) C

Step-by-step explanation:

1. The blue algae has an initial mass of 20 kg and doubles its mass every hour. Then after t hours, the mass of blue algae is

2. The green algae has an initial mass of 160 kg and grows at a constant rate of 0.20 kg per minute. Then after t hours (60t minutes), the mass of green algae is

Part I) At t=3:

The mass of green algae has 196-160=36 kg more mass at 3 hours.

Part II) At t=4:

The blue algae has 320-208=112 kg more mass at 4 hours.