Since 1/5 = 1/7, so its 1u. Since steven has 5 parts..total is 5u and derek 7 parts..so 7u. Total 12u .

12u=72-12 since 6 years later

12u=60

U=5

Raymond Ng can u help with this Q just curious on how u solve it

Total age =12u=60

Derek in 6 years = 7u+6= 41

Chk - steven age in 6 years will be 5u+6= 31. Derek age = 41. 41+31=72.

60 years old

60 yrs old 1 unit = 12 5 units = 5x12 =60

Thanks so much. Appreciate your detail explanation.

You are most welcomed!

7+2=9 7-2=5

4

Besides guess and check, we may draw a model diagram: we draw 2 bars, one long and one short to represent the two numbers. The difference between the bars represent the quantity 5. When we remove 5 from the longer bar, we will have two equal bars with a total of 4 (9 - 5=4). Now we know that the shorter bar represents 2 (4/2=2). The longer bar is 2+5=7. Therefore, the larger number is 7, smaller number is 2. Some children may need a visual approach to solve this.

(9 - 5) ÷ 2 = 2

Once the sum and difference of two numbers are known, Larger number = (sum + difference) ÷ 2 Smaller number = (sum - difference) ÷ 2

another way of looking at it

(D+C) + (D-C) = 9+5 2D = 14 D = 7 C = 2

2

Answer is 4

Oops wrong

This is one of the most difficult question to explain to kids. It just involved simple maths of first line minus second line to get rid of diamond but most don't get it when we tell them +ve minus -ve is actually plus both numbers

Hi, hope this helps.

2

7

Answer: 2 Apply Model drawing

(D+C)-(D-C)=9-5 D+C-D+C= 4 C+C=4 C= 2

2

4

Using model method

2

2

2 use guess and check

If lower Pri, then use guess and check. Possibilities are:- 9 + 0 8 + 1 7 + 2 (✔️) only this is possible. 6 + 3 5 + 4

(9-5)÷2=2

2

Is there a way to solve this question

This method of solving may be too abstract for most students in the primary school. It involves algebraic thinking. The model method is more visual and make the problem accessible for students in primary school before they learn algebra.

I always bang my head trying to teach this to my son. Frustration on all sides. Why they wish to test this type of algebraic qn at primary level without teaching algebra when they will so easily learn to solve this w simultaneous equations just a fee years later at secondary school always boggles me.