Omar paved a 6 foot walkway using 20 stones. He now wants to extend the walkway to 9 feet. How many more stones will he need to buy?

Question

anonymous · Answer

Apply proportional ratio:
x stones/ 9 ft = 20 stones/ 6 ft

anonymous · Answer

Set up a proportion:
6/20 = 9/x
x will be the total number of stones.  Then perform x-20 to get the number of additional stones to buy

anonymous · Answer

@wombat: I've learnt it from you :D

anonymous · Answer

aren't proportions amazing X)

anonymous · Answer

thanks guys

anonymous · Answer

Notice that x is the number of stones needed for 9 ft, 
Since we already had stones for 6 ft,
=> We only need x - 20  stones MORE :)

anonymous · Answer

Good one @Chlorophyll

anonymous · Answer

@wombat AFTER you ; )

anonymous · Answer

haha age before beauty :P @Chlorophyll