Each drink uses 1.5 cups because 1/4 cup + 1 and 1/4 cup = <<1.5=1.5>>1.5 cups
The pitcher contains 12 total drinks because 18 / 1.5 = <<18/1.5=12>>12
There are 15 cups of lemonade in the pitcher because 12 x 1 and 1/4 = 15
#### 15