The local skating rink pays mary a fixed rate per pupil plus a base amount to work as a skating instructor. she earns $90 for instructing 15 students on monday afternoon. last friday, she earned $62 for working with 8 students. lisa is also a skating instructor. she receives half the base amount that mary does, but she is paid twice as much per student. who would earn more money instructing a class of 20 students?
lisa would earn $120 more than mary.
lisa would earn $65 more than mary.
mary would earn $15 more than lisa.
mary would earn $10 more than lisa.

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.

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step-by-step explanation: