Q5 of 80 Page 42

The sum of three consecutive multiples of 7 is 777. Find these multiples.

(Hint: Three consecutive multiples of 7 are ‘x’, ‘x + 7’, ‘x + 14’)

Let the first of the three multiples be x.

Multiples of 7 differ from each other by 7 units.


∴ The other two multiples of 7 will be (x + 7) and (x + 14).


The sum of the three multiples of 7 = 777.


According to the given condition,


x + (x + 7) + (x + 14) = 777


⇒ x + x + 7 + x + 14 = 777


3x + 21 = 777


⇒ 3x = 777 – 21 (Transposing 21 to RHS)


3x = 756


⇒ x = (Transposing 3 to RHS)


x = 252


The three multiples of 7 are


x = 252


x + 7 = 252 + 7 = 259


x + 14 = 252 + 14 = 266


∴ The three multiples of 7 whose sum is 777 are 252, 259 and 266.


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