Calculating Ratios

Hi,

I have been trying to calculate ratios in Power BI Desktop, but so far I am unable to fathom how to do it.

My requirement is, I need to count the number of events in a column, then divide this by the sum of all numbers from another column in a different table, and then multiply this by a factor of 100000.

Table 1 = All 'Events'

Table 2 = All 'Worked Hours'

Table 3 = Locations

Relationship is set = locationID in events table matches with locationID in Location Table // locationID in Location Table is linked to locationID in events table.

How may this be achieved?

Many thanks for anybody able to support.