In the AD partnership, A capital is $$140,000$ and $D$ is $$40,000$ and they share income in a $3$:$1$ ratio, respectively. They decide to admit $D$ to the partnership.

What amount will D have to invest to give him $20\%$ interest in the capital of the partnership if no goodwill or bonus is recorded?

Select one:

$$ a$.50,000$

b$.60,000$

c$.36,000$

d$.45,000$