Opal paid a total of $210 for a cardigan, a pair of socks and a pair of trainers. She spent ⁴₇ of her money on the pair of socks. The pair of trainers cost 9 times as much as the cardigan. How much more did she pay for the pair of trainers than the cardigan?
Amount that Opal paid for the pair of socks
= ⁴₇ x 210 
= $120

Amount that Opal left after buying the socks
= 210 - 120
= $90

Amount that Opal paid for the cardigan = 1 u
Amount that Opal paid for the trainers = 9 u

Total amount spent on the cardigan and the pair of trainers
= 1 u + 9 u
= 10 u

10 u = 90

1 u = 90 ÷ 10 = 9

Amount that Opal paid more for the pair of trainers than the cardigan
= 9 u - 1 u
= 8 u
= 8 x 9
= $72

Answer(s): $72