Problem 3. In the morning, a dandelion blooms, it flowers yellow for two days, on the third day in the morning it turns white, and by evening it sheds its seeds. Yesterday afternoon, there were 20 yellow and 14 white dandelions on the meadow, and today there are 15 yellow and 11 white.
a) How many yellow dandelions were there on the meadow the day before yesterday

b) How many white dandelions will there be on the meadow tomorrow? [6 points] (
Answer. a) 25 yellow dandelions; b) 9 white dandelions.

Solution. a) All dandelions that were yellow the day before yesterday have turned white yesterday or today. Therefore, there were $14+11=25$.

b) Out of the yellow dandelions from yesterday, 11 turned white today, and the remaining $20-11=9$ will turn white tomorrow.