oG11-綠pS120 ( 查出來了 已解決)

Kath1985

Oneweekacertain truck rental lot had a total of 20 trucks, all of which were on the Monday morning.
If 50 pervent of the trucks that were rented out during the week were returned to the lot on or before
Saturday morning of that week, and if there wereat least 12 truckson the lot that Saturday morning,
what is the greatest number of different trucks that could have been rented out during the week?
(A)18
(B)16
(C)12
(D)8
(E)4
Ans:B
我覺得答案應該是18 因為題目中有說至少 12台車在星期六早上歸還  表示有十二台以上(包含12)的車歸還了可再租出去
所以算式應該寫成  
設租出去的車為R
(20-R) + 0.5R >= 12 可得 R >= 16  變號後 R<=16  
剛才想通了 忘記變號