We know that the goldfish is $10 and the average of the two fish is $7. So, we can ask (10+?)/2 = 7 and work out that the angelfish costs $4.. Or we can say that since average of $7, the total cost is $7*2 = $14, the angelfish is $4. Knowing then that the goldfish costs $6 more than the angelfish, we can find out how many goldfish was bought.

One of the concepts about average is that the average*number of objects = total quantity.

Thanx, Caleb!

My boxes a bit messy. Start with the green then the brown lines are step 2.

Can understand. Thanx. Not messy

Thank you!

Total sweets difference between giving 7 sweets and 6 sweets is 11 sweets. Hence, there are 11 children. Since there is a surplus of 2 sweets if 6 were given, so 11*6+2= 68

Thanx, Yeo n Jacqueline.

Arlene Tan

Alternative approach..

Another way.

Izam Marwasi, don't really understand your method

Hope my attempt to solve this qn helps.

Here's something visual to help students understand the thinking regarding the number of children. For students working on this problem for the first time, it would be good for them to work with counters, chips, etc to 'act it out'. The abstract thinking and calculations can follow after that.

Is this p4 question?

P6!

P4 topics factors n multiples

Adrian Ng, see vei li soo's model

Here is an alternative to working out the answer without using guess and check

thanx, wen kiat. algebra I know too. was looking for non-algebra methods.

Using multiples of 7 & 6

Thanks!

27 ÷3 = 9 sets 9 sets of (3+8) = 99

99

Cause for each set of 8 he gets 3 free: with 27 free that's 9 sets, so 9x8 + 27 = 99

27➗3=9 9X8=72 72 + 27 =99

99