Jack scored 3 + 5 = <<3+5=8>>8 points.
Together, Jon and Jack scored 8 + 3 = <<8+3=11>>11 points.
So, Tom scored 11 - 4 = <<11-4=7>>7 points.
Thus, Jon, Jack, and Tom scored a total of 3 + 8 + 7 = <<3+8+7=18>>18 points.
#### 18