You can assume that the CQLY (not CMQLY) can be 20% and the rest of the year went up to 80% hence you would have something like 80/(48+8)= 1.428. or a 42% percent weighted growth. Now typically the calculate the figure comparing CQLY to CQTY, which would be extremely inflated number 80/20= 400% growth, or they may use CQTY to LQTY, which will throw strange numbers every quarter. Also you can do the same calculation based CQTY to Last six month average.

Basically there are many different ways to calculate this, it all depends on client’s comfort level. I hope this helps you out.