問題maths

某人以港幣150000元(HK$)買入若干英鎊,兌換率為英鎊1=HK15.00,把該款項作一\定期存款,為期30天,年利率14.6%

(a)問他買了多少英鎊?
(b)以英鎊計算,求30天後本利和.(設1年=365天,利息以單利計算)
(c)若他把(b)部的本利和以英鎊1=HK$14.50的兌換賣出,問他可得回多少港元?
(a)
他買了英鎊
=150000/15
=10000
(b)
30天後本利和
=10000*(1+0.146/365)^30
=10120
(c)
他可得回港元
=10120*14.5
=146740
設2a=3b=5c

(a)求a:b:c的比

(b)若a-b+c=55,求c
(a)
令
2a=3b=5c=k
a=k/2, b=k/3, c=k/5
a:b:c
=k/2:k/3:k/5
=1/2:1/3:1/5
=15:10:6
(b)
a:b:c=15:10:6
令a=15s, b=10s, c=6s
a-b+c=55
15s-10s+6s=55
s=5
c=6*5=30