Question

a box contains 100 pens.In each box there are 38 black pens and 42 blue pens,while the rest are green pens.Mr.Cane buys 6 boxes of pens.How many green pens does he have in total

Answer 1

120 of the pens are green.
100-(38+42)=?
100-80=20
20x6= 120
therefore 120 pens are green.

Answer 2

If he has 6 boxes with 100 pens in each box that's 600 pens.

38 x 6 = 228 pens are black

42 x 6 = 252 pens are blue

228 + 252 = 480 black and blue pens

600 - 480 = 120 green pens

Hope this helps. :)