I am doing questions on percentage increases and decreases. There is a question at the end which reads:
After general service and tune-up a car will do 20% more kilometres to the litre. Determine the resulting percentage saving in fuel.

??? The answer in the book is:
16 and 2 thirds percent.

??? How so?

Question

I am doing questions on percentage increases and decreases. There is a question at the end which reads:
After general service and tune-up a car will do 20% more kilometres to the litre. Determine the resulting percentage saving in fuel.

??? The answer in the book is:
16 and 2 thirds percent.

??? How so?

anonymous · Answer

If we assume that the original km/litre was 100, and it increased to 120, we take 120 as the new 100%. 20 of 120 is 16.67%

anonymous · Answer

Oh okay we can just make up any amount in this scenario and just figure it out... I was just like... ummm... 20%?? Okay that makes sense.

anonymous · Answer

Well 100 is an ideal amount to 'make up', since we're dealing with percentages.

anonymous · Answer

thanks