The expressions for the payment made to Mary are,
(Monday) 90 = 15m + b
(Tuesday) 62 = 8m + b
where m and b are the fee per student and the base fee, respectively. Solving for m and b, the values are 4 and 30.
The equation that represents Mary's earning is
y = 4x + 30
For 20 students,
y = 4(20) + 30 = 110
For Lisa's earnings,
y = 8x + 15
Substituting 20,
y =8(20) + 15 = 175
Thus, Lisa would earn more than Mary by $65.
We have been given that a hiker begins in a valley at 150 feet below sea level. When the hiker reaches the highest point on the trail, he is 579 feet above sea level. We are asked to find change (in feet) in elevation of the hiker.
To find change in hiker's elevation we will subtract hiker's initial elevation from hiker's elevation at the end of trail.

We are subtracting negative 150 because at the beginning of trail hiker was 150 feet below sea level.


Therefore, the change in hiker's elevation is 729 feet.
Multiply .04 and $36,920... Giving you $1,476.80 as the amount for the 4% raise. Subtract the raise from this year's salary giving you $35,443.20