Please help me with this question

The flowers are 2/15 and shrubs are 3/10
Step by step
The flower he uses are
2/5 x 2/5 = 4/15
The shrubs he uses are
(1-2/5) x 1/2 = 3/10
The flower he left are
2/15 - 4/15 = 2/15
The shrubs he left are
3/5 - 3/10 = 3/10
Understand??