Answer: The salesperson must sell 20 memberships to make the same amount of money under both plans.
Step-by-step explanation:
Let x be the number of memberships.
In first plan,
Weekly salary of $300 plus a commission of $15 for each membership sold.
i.e. Earning (weekly) = 300+15x
In second plan,
The other plan offers no salary but pays $30 commission on each membership sold.
i.e. earning = 30x
According to the question, when [tex]300+15x=30x[/tex]
[tex]\Rightarrow\ 300=30x-15x\\\\\Rightarrow\ 300=15x\\\\\Rightarrow\ x=\dfrac{300}{15}\\\\\Rightarrow\ x=20[/tex]
Hence, the salesperson must sell 20 memberships to make the same amount of money under both plans.