Answer:
10 shirts have to be purchased.
Explanation:
The Cactus Company equation: 15 (base fee) + 7x (7 being the price, x being the number of shirts purchased).
The Flower Company equation: 35 (base fee) + 5x (5 being the price, x being the number of shirts purchased).
Our final equation: 15+7x = 35 + 5x
-5x -5x
15+2x = 35
-15 -15
2x = 20
/2 /2
x = 10