Question

Mr Tan has an equal number of pens and pencils. He puts the pens in bundles of 8 and the pencils in bundles of 12. There are 15 bundles altogether. How many pens are there?

Answer 1

120 ah ? pls replay frnd....

Answer 2

let the number of bundles formed by pens be x;
let the number of bundles formed by pencil be y.
acc. to 1st condition;
8x=12y
therefore 12y-8x=0----(i)
acc.to the 2nd condition;
y+x=15----(ii)
multiplying (ii) by 8;
8y+8x=120---(iii);
adding (i) and (iii);
12y-8x=0
8y+8x=120
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20y=120
y=6;
therefore x=15-y=15-6=9(from eqn (ii));
total no. of pens=8x=8*9=72 pens.