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