Answer:
To answer the question above, evaluate the number of cookies each of them placed on a tray. The calculations are shown below,
Ronny C1 = 0.15 x 20 = 3
Celina C2 = 3
Jack C3 = 0.30 x 20 = 6
Michelle C4 = 20 - (3 + 3 + 6) = 8
From the calculation above, Michelle placed the most number of brownies on the tray.