Green grapes = G
Red grapes = 3G + 7
Raspberries = G - 5
G + 3G + 7 + G - 5 = 102
5G + 2 = 102
5G = 100
G = <<20=20>>20
3 * 20 + 7 = <<3*20+7=67>>67
There are 67 red grapes.
#### 67