Ricky bought flowers for susan he spent a total of $14.85 and bought 13 flowers if you knows lillys cost $1.25 and tulips cost $.90 how many of each flower did he buy susan

Given:
Total amount spent = $14.85
Total number of flowers = 13
The cost of a lily = $1.25
The cost of a tulip = $0.90

Let x =  the number of lilies bought
Let y =  the number of tulips bought

Therefore
x + y = 13                             (1)
1.25x + 0.9y = 14.85           (2)

From (1),
y = 13 - x                             (3)
Substitute (3) into (2).
1.25x + 0.9(13 - x) = 14.85
0.35x + 11.7 = 14.85
0.35x = 3.15
x = 9
y = 13 -x = 4

 
9 lilies
4 tulips

Ummm ok. for informing us