Final answer:
The broker must list the property for sale at the price requested by the owner.
Step-by-step explanation:
The broker must list the property for sale at the price requested by the owner, which is $70,000. It is the broker's responsibility to carry out the owner's instructions and not impose their own valuation on the property. The broker's professional duty is to act in the best interest of the owner and work towards achieving their desired goals.