Project Euler Problem 18

with open('pe18.txt', 'r') as file:
    numbers = [[int(num) for num in line.split()] for line in file]

numbersRev = reversed(numbers)


for line in numbersRev:
    for item in range(0, len(line)):
        if item < len(line) - 1:
            a = line[item]
            b = line[item + 1]
            c = max(a, b)
            numbers[numbers.index(line) - 1][item] += c

print(numbers[0][0])