to travel the Erie Canal a boat must go through box that raise or lower the boat traveling East a boat would have to be lowered 12 feet and Amsterdam 11 feet tribes Hill and 8 feet at Randall by how much does the elevation of the boat change between Armstrong and Randall
so you are lowering 12 feet down, then 11 feet down , then 8 feet down.
so the total amount lowered is 12 + 11 + 8 , which is a total elevation change of 31 feet