Ben Looi's answer to Ho Lee Ling's Primary 5 Maths Rate & Ratio question.

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Ben Looi
Ben Looi's answer
18 answers (Tutor Details)
1st
This is tricky. You need to switch between discount and no discount. But step by step, let's figure this out. First, how much does 3 tickets cost? It's 3 x $7.50, BUT WAIT! Got DISCOUNT of $5, so minus 5 from full price.
ANS: 17.50 for 3 tickets.
Now you must use guess and check method.
Since the amount Mr Faroek spent is 172.50, it looks very close to 17.50 x 10 or 175. SO I am guessing the answer is close to that. Let's see how many tickets can 175.00 buy.
175 / 17.50 = 10 sets of 3 tickets

But this is too many. So let's guess with 1 set less, which is 9 sets of 3 tickets.
175 - 17.50 = 157.50
So Mr Faroek spent 172.50, which means he bought at least 9 sets of 3 tickets, and then maybe one or two more tickets., but without discount for the remainder.

The amount he spent on undiscounted tickets is:
172.50 - 157.50 = $15

so from here, it is quite easy. $15 is the price of 2 x $7.50 tickets,

so he bought 9 sets of 3 (9 x 3 = 27) and 2 tickets, or 27+2 = 29 tickets.