# Worked Examples

Identify the rule

(21 â€“ 13) â€“ (15 â€“ 11)

= 8 - 4

= 4

Verify the rule

(16 - 9) - (11 - 7)

= 7 - 4

= 3

Apply the rule

â€‹

(14 â€“ 5) â€“ (9 â€“ 6)

= 9 - 3

= 6

Rule: (c â€“ a) â€“ (d â€“ b) = e

(The rule holds good.)

**Answer:** 6

Identify the rule

= 2 + 5 + 7 + 6

= 20

Verify the rule

= 4 + 6 + 9 + 3

= 22

Apply the rule

= 6 + 2 + 3 + 5

= 16

Rule:

The rule holds good.

**Answer:** 16.

= 42 Ã· 2

= 21

Verify the rule

= 38 Ã· 2

= 19

Apply the rule

= 44 Ã· 2

= 22

Rule: (a + b + c + d) Ã· 2 = e

The rule holds good.

**Answer:**22

Identify the rule

= 4 + 7

= 11

Verify the rule

= 3 + 7

= 10

Apply the rule

= 9 + 4

= 13

Rule:

The rule holds good.

**Answer:** 13

Identify the rule

Verify the rule

Apply the rule

Rule:

The rule holds good.

**Answer:** 144

Identify the rule

Verify the rule

Apply the rule

Rule:

The rule holds good.

**Answer:** 4

Identify the rule

2^{2} + 6^{2} + 8^{2} + 3^{2}

= 4 + 36 + 64 + 9

= 113

Verify the rule

3^{2} +7^{2} + 4^{2} + 5^{2}

= 9 + 49 + 16 + 25

= 99

Apply the rule

5^{2} + 9^{2} + 6^{2} + 1^{2}

= 25 + 81 + 36 + 1 = 143

Rule: a^{2} + b^{2} + c^{2} + d^{2} = e

The rule holds good.

**Answer:** 143