Let’s break it down. The product of their ages is 72. So what are the possible choices?

2, 2, 18 – sum(2, 2, 18) = 22
2, 4, 9 – sum(2, 4, 9) = 15
2, 6, 6 – sum(2, 6, 6) = 14
2, 3, 12 – sum(2, 3, 12) = 17
3, 4, 6 – sum(3, 4, 6) = 13
3, 3, 8 – sum(3, 3, 8 ) = 14
1, 8, 9 – sum(1,8,9) = 18
1, 3, 24 – sum(1, 3, 24) = 28
1, 4, 18 – sum(1, 4, 18) = 23
1, 2, 36 – sum(1, 2, 36) = 39
1, 6, 12 – sum(1, 6, 12) = 19

The sum of their ages is the same as your birth date. That could be anything from 1 to 31 but the fact that Jack was unable to find out the ages, it means there are two or more combinations with the same sum. From the choices above, only two of them are possible now.

2, 6, 6 – sum(2, 6, 6) = 14
3, 3, 8 – sum(3, 3, 8 ) = 14

Since the eldest kid is taking piano lessons, we can eliminate combination 1 since there are two eldest ones. The answer is 3, 3 and 8.

Valuable suggestion from the retired professors will be helpful for restructuring of an organisation. Hence, management should involve such experienced people. Seeking permission from the employees is not the right course of action.

By trial and error method from the given options,

as 54 - 45 =  (1/11) x (45+54)  = 99/11  = 9

Hence this satisfies the given conditions.

Then the woman's husband age is 54.

Let their ages be x, y, z
Hence given that x + y + z = 65
Now, six years ago x age is x - 6, y is y - 6 and that of z is z - 6
Then the sum of their ages six years ago is (x + y + z) - (6 + 6 + 6) = 65 - 18 = 47

Net asset value (NAV) is value per share of a mutual fund or an exchange-traded fund (ETF) on a specific date or time. It  is the value of an entity's assets minus the value of its liabilities, often in relation to open-end or mutual funds, since shares of such funds registered with the U.S. Securities and Exchange Commission are redeemed at their net asset value.

Using pythagarous theorem,
distance travelled by first train = 36x5/18x30 = 300m
distance travelled by second train = 48x5/18x30 = 400m
so distance between them =√( 90000 + 160000) = √250000 = 500mts.

Let their present ages be 13x and 17x.
Then, 13x-4/17x-4 = 11/15.
Solving this, we get x = 2.
Required ratio = 13x2 + 6/17x2 + 6 = 32/40 = 4/5.