Can someone please help, I want to achieve the following.

2 worksheets, results and data
Data sheet has the following colums
Size Wegcost Cempcost
0.75 £120 £100
1.1 £90 £95
1.5 etc etc
1.5
2.2
3.0
4.0
5.5
7.5

Results sheet has 3 cells say A1 and B1
A1 has a combo box which lists the sizes from data sheet colum A1
B1 has a combo box which lists the name Weg-Cemp.
How do get the cost of a size based on which name is chosen.
There is a total cell say F1 which is the SUM of B1:E1
Can someone help, my brain is in overload.
many thanks
Andy