sum in between two same name or color

[pracas]

Hi, I am doing a project. I have excel file with huge data. I want to add data between two randomly placed data between two rows with same color or same name.
For example;
total
cost -
home.....10
car....20
.
cost -
rent...20
.
.
cost -
.
.
cost
.
.
.


In which, i want to add from one cost data to another cost data continuously.
I would appreciate any help!!!! Thanks!!!!

[JBeaucaire]

The first formula goes in C3, then copy donw.

Data Range

	A	B	C	D
1	total
2	cost
3	car	30		=IF(A3="cost", SUM(INDEX($B$1:$B2, LOOKUP(2, 1/($A$1:$A2="cost"), ROW($A$1:$A2))):$B3),"")
4	home	45
5	fuel	34
6	cost		109
7	car	20
8	home	16
9	fuel	5
10	cost		41