Question

Mark uses 3 1/8 pounds of seed to fill the the birdfeeders in his backyard, but he only has 1 1/2 pounds of seeds. How much seed does he need to buy?

Answer 1

Total weight of seeds =3 ⅛

Weight of seeds he has = 1 ½

Required no. of seeds = 3⅛ - 1½

$\frac{25}{8} - \frac{3}{2} \\ l.c.m \: of \: 8 \: and \: 2 \: is \: 8 \\ \frac{25}{8} - \frac{12}{8} \\ = \frac{25 - 12}{8} \\ = \frac{13}{8}$