import sys
amounts = [100, 200, 50]
refunds = [0, 20, 50]
assert len(amounts) == len(refunds)
net = [a-r for a,r in zip(amounts, refunds)]
assert net == [100,180,0] and sum(net) == 280
print("interpreter:", sys.executable)
print("version:", sys.version.split()[0])
print("net per order:", net)
print("total net:", sum(net))