how to change rows into columns

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T-SQL

Hi Everyone.

I don't have any experience in writing queries. Please help me to sort out this.

i've a table like

col1   col2    col3 
----------------------  
1       25     comp
1       27     elec
2       20     comp
3       13     elec
3       17     comp
3       23     comp
4       27     elec

i want to get output like this

col1   comp   elec
-------------------------
1      25     27
2      20      null
3      13     40(13+27)
4      null   elec

Thanks in Advance.
Anil