The correct option is C LXX
We know that X = 10 and L = 50.
When a Roman numeral with the larger value is on the left, we add the values together and when it is on the right, we subtract the values.
Thus, XXX = 10 + 10 + 10 = 30 and XL = 50 - 10 = 40.
Therefore, XXX + XL = 30 + 40 = 70.
But, 70 = 50 + 10 + 10 = LXX.
Thus, we get LXX when XXX is added to XL.