Combining two columns

I have a VBA script that extract the data from my excel workbook and saves it as a .csv file.

I have all but got most of it too work, except where i need to extract data from 2 columns into one cell.

I've been able to extract single row & column data using the following

       Cells(iRow, 5) = "=Data!RC[-1]"
       Cells(iRow, 6) = "=Data!RC[-1]"
       Cells(iRow, 7) = "=Data!RC[-1]"

This is where i'm unsure of how to combine data from Row 2 column 7 and Row 2 Column 8. the data then needs to be inserted into Column 8 in the output file. This is what i have, but it doesn't work. It stops my whole macro from running.

       Cells(iRow, 8) = "=Data!RC[-1]" + "=Data!RC"

any help greatly appreciated.