Since Kobby is 5 years older than his brother, his brother's age is 5 years less than that of Kobby's age.

Kobby is 13 years now.

Brother's age = 13 - 5
Brother's age = 8

Let x be the number

A certain number (x) is subtracted from 12 → result = 12 - x

The result is multiplied by 3 → (12 - x) x 3

The answer is 21 → (12 - x) x 3 = 21

Now solve for x

(12 - x) x 3 = 21

a(b - c) = a x b - a x c

(12 - x) x 3 = 12 x 3 - 3 x x

12 x 3 - 3 x x = 36 - 3x

36 - 3x = 21

Move the - 3x to the right side of the equation and 21 to the left

- 3x becomes 3x at the right (when negative crosses the equal to sign becomes positive

21 becomes -21 at the left

36 - 21 = 3x

15 = 3x

Divide both sides of the equation by 3 to make x the subject

15/3 = 3x/3

5 = x

∴ x = 5

You can verify

12 - 5 = 7 (Result)

7 x 3 = 21 (Answer)

The Cardinal Point

We can draw the diagram below from the above information

We can apply pythagoras theorem to calculate how far she was from her starting point

NOTE: the c is the longest part or the side faceing the right angle (90^o)

We can redraw our diagram to:

Now solve for the value of x

Take the square root of both sides to get ride of the square

Total pocket money given = 3 x 1.5 = GH₵ 4.5

Amount left = Initial Amount - Amount Given = 5 - 4.5 = GH₵ 0.5

Priscila's age = k

Mary's age = b

Mary is 15 years older than Priscila. This means that if you add 15 years to Priscila's age, you will get Mary's age or if you subtract 15 years from Mary's age you will get Priscila's age.

Mary's age = Priscila's age + 15

b = k + 15

Now let 15 be alone at the right hand side of the equation, thus move the k to the left hand side. Its positive(+) so it becomes negative (-)

b - k = 15

Amount Left = Total Amount Needed - (Amount contributed by the 12 towns + Amount contributed by the district assembly

Each (Each and every) community contributed GH₵ 25,000.00, to get the total amount contributed by the communities, you have to multiply the amount contributed by each by 12 (Total number of communities which contributed)

Amount contributed by the community = GH₵ 25,000.00 x 12 = GH₵ 300,000.00

Total amount contributed = Amount contributed by the communities + Amount contributed by the District Assembly

Total amount contributed = GH₵ 300,000.00 + GH₵ 30,500.00 = GH₵ 330,500.00

Amount left for the project = Total Amount Needed - Amount Contributed

Amount left for the project = GH₵ 375,000.00 - GH₵ 330,500.00 = GH₵ 44,500.00