maths

Let the price of one cake be X

Buying a dozen of cakes at A equals to
12*X*80% = 9.6X

Buying a dozen of cakes at B equals to
(12/4)*3*X=9X

Bakery B offers a greater discount for buying a dozen of cakes.

Let the price of 1 cake is $1
Bakery A:1x12x(1-20%)
=9.6

Bakery B:(3+1)/12 x3x1
=3x3x1
=9
Bakery B offers a greater discount for buying a dozen of cakes.
希望幫到你啦^o^

A店以 8 折出售蛋糕
B店提供 買 3 送 1 的優惠
若兩店蛋糕的售價相同
問在哪間店買 一打蛋糕 所獲折扣較大?

2006-11-04 13:03:28 補充：
弄錯了不是售價相同, 是標價相同

Let x be the marked price of 1 cake

For Bakery A,
if we buy a dozen of cakes,
price:
12x *( 1 - 20% )
= 9.6 x

For Bakery B,
if we buy a dozen of cakes,
we only need to buy 9 cakes as buy 9 cakes will get 3 free cakes.
price = 9x

so, Bakery B offers a greater discount for buying a dozen of cakes