grouping in crystal report 10

hi all, i have problem with grouping data in crystal report 10... this is example of my report after grouping:

(name).......[income]
--------------------
(a).............[2500]
(a).............[2000]
(b).............[4500]
(b).............[1500]
(b).............[1000]

on my report, i want to show only total of income, after it's grouped by name... so this is what i want...

(name)......[income]
-------------------
(a).............[4500].............'---> 2500 + 2000
(b).............[7000].............'---> 4500 + 1500 + 1000

anybody could help me? :ehh:
thnx...
-aldosan-