Part A is basically asking you for the GCF (greatest common factor) between 63 and 36. To find this you find all the numbers that can be multiplied to form each number.
36:
1 * 36
2*18
3*12
4*9
6*6
63:
1*63
3*21
9*7
The GCF is 9.
Part B is asking how much the GCF can go into each type of flower.
4 rows of geraniums
7 rows of marigolds