I am trying ti look up and match info from 2 columns, from this add the numbers together in a third column and placing the answer in a cell

example data


Line Group Qty
1 77 10
1 55 20
2 88 10
2 66 20
2 88 32
2 66 57
2 88 28
3 88 15
3 66 20
3 88 10
3 66 20
4 88 15
4 66 25

so what i need is from line 2 group 88 = total 70 thanks in advance