I understand the point you are making but the problem is that of a conflation and not that of equivalence. The price of gas is 10% higher this week than last w

I understand the point you are making but the problem is that of a conflation and not that of equivalence. The price of gas is 10% higher this week than last week. A.k.a.: the price this week is 1.1 times the previous week. I was going 50% faster than my friend was. A.k.a.: my speed was 1.5 times his'. You were going 100% times faster than me, so you were going twice as fast as I was. Change factor. 1 + the change / 100.