Marco is selling floral arrangements. each arrangement uses 1 vase and 11 orchids. each case cost marco $4.00. let c be the total cost of the arrangement and r be the cost of 1 orchid. which equation should marco use to find the total cost a. 11= c + 4r b. 11c = r + 4 c. c= 4r + 1 d. 11r + 4

1. The information given in the problem is:
 
 - Each arrangement uses 1 vase and 11 orchids.
 - Each case cost Marco $4.00.
 - C: the total cost of the arrangement.
 - r: the cost of 1 orchid.
 
 2. Therefore, you must multiply the cost of 1 orchid by the 11 orchids that he uses in each arrangement, and then, you must add the cost of 1 vase, as below:
 
 C=11r+4
 
 3. Finally, you can conclude that the correct answer is the last option:
 
 D)C=11r+4

Logical equivalent of the give question is its contrapositive