Desription: Distance and time meassuring and calculating

The storry: The farmer has got a farm. His house is close to $40m$ to river. In distance $150m$ in horizontal line there is a barn. One day the farmer saw the barn was burning. Quick decision to get $2$ buckets, go to the river, take the water and as quickly as it possible and using the shortest path $($way$)$ he need to put out the fire...

What's the shortest distance, when we know, that the barn is $60m$ away from river?

How to calculate the time for getting to the fire barn, when you know that with heavy buckets with water the farmer will go slower?

How calculate the time, cost of fuel, and the shortest distance when we use the fire brigade with firetruck?

Please use Excel to calculate all above mention indicators...