Example:
Before
column A Column B Column C
BB20
41100 50 100
41200 50 20
41300 30 22
BB45
41250 15 40
BB88
42100 50 100
42300 50 100
After
column A Column B Column C
BB20
41100 50 100
41200 50 20
41300 30 22
Subtotal 130 142
BB45
41250 15 40
Subtotal 15 40
BB88
42100 50 100
42300 50 100
Subtotal 100 200
Total 245 382