Lawrence had some money. He spent 3/5 of it on 4 similar highlighters. With the rest of his money, he bought another 2 such highlighters and 10 rulers.
(a) What fraction of his money was spent on buying 10 rulers? Give your answer in its simplest form.
(b) In a sale, Lawrence would be given 1 free ruler for every 12 rulers bought. How many rulers would he get altogether if he had spent all of his money at first on rulers?
set all of his money as x.
3/5x is 4 highlighters, so 3/10x is 2 highlighters.
he only spent 1/10x of his money buying 10 rulers, which answers the first question given.
(b) he spends all his money buying rulers. which means ignoring the free rulers, he could buy 100 rulers. but then, since there are 8*12 = 96, we know he gets an extra 8 rulers and hence have 108 rulers if he spent all his money at first on rulers.