Report Builder Query Concating two fields

I have two fields that I need to concatenate after I have performed a calcutation. I am taking a school year and subtracting 5 years.

School Year = 201314. I want the result to be 200809 so that I can select any courses that have a School Year greater than 200809.

I have tried many variations of:

LEFT(sysvar.cur_schyr,4) - 5 + RIGHT(sysvar.cur_schyr,2) - 5 as "B4SchYr" this adds 2009 + 08 and gives me 2017 when I want 200809 returned. How do I treat the numeric strings as characters?

Thanks.