Jaden's age is 1/8 of his mother's age. His mother will be 40 years old in 8 years. In how many years will Jaden's age be 3/7 of his mother's age?

His mother will be 40 in 8 years. So, she is 32 now.

1/8 of his mother's age is 4, so, currently Jaden is 4 years old.

The difference are 28 years.

If he is currently 4 in 17 years he will be 21 years old and his mother will be 49,

21 is 3/7 of 49.

Therefore, the correct answer is, in 17 years.