Question

Ivan has completed 45% of his walk. He has already walked 9 km. How much farther does he have left to walk?

I don't understand how to do this. Could you please help and show me how you got this answer? Thank you.

Answer 1

45% of the total = 9

.45(x) = 9

divide both sides by .45

x = 9/.45

That will give you the total distance.

subtract 9 from that answer to get how much farther.

Answer 2

45% is just about half. So, you know right off he has about 9km left to go. (This is just for a sanity check)

So, the whole walk is 9/.45 = 20km
20-9 = 11 km left to go

The key idea here is figuring the total distance if you know some of it and the % that represents.

If you want to know what to divide by what, think of something easy.

If 9 kn were half the distance, the whole would be 18km, right?

That is 9 / (1/2) = 9*2 = 18
But you only have 45%, or .45
So, divide by .45 -- you expect a number a little more than 18.

Knowing a part and the fraction it represents, just divide the part by the fraction. Play around with some values till you feel comfortable with the idea.