In this question, you are given the average cofactor mass per cell (77.91pg) and the total cells count(10^5 cells). You are asked how much cofactor that will be found from those cells(microgram= 10^6 picogram). Then the calculation would be:
Cofactor mass= cofactor per cell * cell count= 77.91pg/cell * 10^5 cells= 7.791 x 10^6pg
Then convert the picogram(pg) into microgram: 7.791x 10^6pg/ (10^6pg/microgram)= 7.791 microgram
