a) How many eggs did Mr Lee buy from the shop?

Source: ?

a) How many eggs did Mr Lee buy from the shop?

Source: ?

ChiefKiasu

Let T be the total number of trays.

Let C be the total number of carton boxes.

(1) C = T + 26

(C x 12) – 6 = T x 30

=> 12C – 6 = 30T

=> 12C = 30T + 6

=> (2) C = (30T + 6)/12

Substituting (1) into (2), we get

T + 26 = (30T + 6)/12

12T + 312 = 30T + 6

18T = 306

T = 17

So he bought 17 x 30 = **510 eggs** from the store #

teohyuquan

sorry but I still don’t understand. Is there a simpler method?

ChiefKiasu

Um… can someone else come up with a model answer? I’m pretty bad at model answers.

The first equation C=T+26 simply states that there are 26 more carton boxes than trays.

The second equation (C x 12) – 6 = T x 30 is now counting the actual number of eggs in each carton and tray. So (Cx12) – 6 is the total number of eggs repackaged, which is of course equal the Tx30 which is the original number of eggs Mr Lee bought.

So I reworked the equation until I get C which I then substituted in the equation for C in the first equation.