There are 10 x 15 = <<10*15=150>>150 squares in a grid.
4 x 6 = <<4*6=24>>24 squares are colored red.
There are 2 + 2 = <<2+2=4>>4 rows that are all blue.
Thus, a total of 4 x 15 = <<4*15=60>>60 squares are colored blue.
24 + 60 = <<24+60=84>>84 squares are color red or blue.
Therefore, 150 - 84 = <<150-84=66>>66 square are green.
#### 66