First we need to find out what her increase is so 50% of 1000 is is 500 so from 12am to 1am she made
1500
from 830 to 12 am gives us 4 1/2 hours so she got paid 4500 for those hours adding on the past 12am and we get
6000 as the total amount she made
Recall that
d/dx sech(x) = - sech(x) tanh(x)
d/dx tan⁻¹(x) = 1/(1 + x²)
Then by the chain rule,
dy/dx = - sech(x) tanh(x) / (1 + x²)
19.5 in difference
difference indicates that you'll be subtracting so 29 3/4 - 10 1/4 = 19.5