The local skating rink pays mary a fixed rate per pupil plus a base amount to work

The correct option is :

Lisa would earn $65 more than Mary.

Step-by-step explanation:

Let 'b' define base salary of Mary.

Let 'm' define the fee per student.

As per given information, Mary's expressions become:

For Monday:   .... (1)

For Tuesday:     ....(2)

Subtracting (2) from (1) to get the value of m

m = 4

b = 30

So, the complete equation that represents Mary's salary is :

For 20 students, the salary becomes:

= $110

Similarly, Lisa's earnings can be shown as :

So, for 20 students, Lisa's salary is :

= $175

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Now difference between both girl's salary = dollars.

So, the correct option is :

Lisa would earn $65 more than Mary.