Calculating Operational Downtime

I cannot figure out how to calculate the operational downtime via formula. Attached I have a sample of what I am trying to figure out. We occasionally have a machine go down on lets say 01APR at 03:15 then we fix it on 03APR 19:37. I need a formula to figure out both How many minutes the machine is down in total and a separate formula to figure out how many minutes of operational time we missed. Please help I cannot wrap my head around this.