elect the correct answerAverage age of A, B and C is 10 year less than age of C. If ratio of age of A, B and C is 3 : 4 : 5 then what is the sum of age of A & C ?Options85 year72 year80 year78 year

The problem states that the average age of A, B, and C is 10 years less than the age of C. This means that the sum of the ages of A, B, and C is 3 times the age of C minus 30 years (since the average is calculated by summing the ages and dividing by the number of people, and in this case, the average is given as C's age minus 10 years).

The problem also states that the ratio of the ages of A, B, and C is 3:4:5. This means that if we let x be a common factor, the ages of A, B, and C can be represented as 3x, 4x, and 5x respectively.

So, we can set up the following equation based on the information given in the problem:

3x (A's age) + 4x (B's age) + 5x (C's age) = 3 * 5x (3 times C's age) - 30

Solving this equation gives:

12x = 15x - 30

Subtracting 15x from both sides gives:

-3x = -30

Dividing both sides by -3 gives:

x = 10

So, the ages of A, B, and C are 30 years, 40 years, and 50 years respectively.

The sum of the ages of A and C is 30 + 50 = 80 years.

So, the correct answer is 80 years.