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-yO mAmA
make two triangles. make the bottom of one triangle 135 as the shadow and "x" as the height. the other traingle should have 9 at the bottom and 5.3 as the height. then make a proportion
So, what is the case in which he uses the least coins? can he use 1 coin? no, there isn't a 35 cent coin. can he use 2 coins? yes! he can use 25+10 cent coins!
now, the largest number of coins means the coins of the smallest value: so using only 5 cent coins. How many would this be?
we have to divide:
35/5=7
so we would use 7 coins.
And the difference is 5: 7-2 is 5.
Yes it is good luck too you