Box of 3 spoons, original = $9

Box of 3 spoons, discounted price = (100% – 10%) x $9 = $8.10

Packet of 4 forks, original = $12

Packet of 4 forks, discounted price = (100% – 20%) x $12 = $9.60

LCM of 3 and 4 —> 12

1 set, original = 12 spoons and 12 forks (24 cutlery items) = (12 ÷ 3) x $9 + (12 ÷ 4) x $12 = $72

1 set, discounted price = 12 spoons and 12 forks (24 cutlery items) = (12 ÷ 3) x $8.10 + (12 ÷ 4) x $9.60 = $61.20

Diff in both sets (saved) = $72 – $61.20 = $10.80

No. of sets = $43.20 ÷ $10.80 = 4

Total forks Sally bought = 4 x 4 = 16 (a)

Total paid, discounted price = 4 x $61.20 = $244.80 (b)

Hope you understand and all the best for your exams! :))

May i know if the answer for a) should be 4*12 forks =48 

Thank you Suma for helping