A) When working out the second equation i read the requirement as how long the fuel left would last and came up with
t = c/b time = currentFuel/burnRate
t = 80 / 2 = 40
by reworking the 1st equation you are working out how long we’ve been flying for aren’t you?
t = (-c + m ) / b
t = (-80 + 100) / 2 = 20 / 2 = 10
[Starting with c as 0 you happen to get an answer of 50 for time on max fuel…]
B) In manipulating the equations you expanded -(b * t) to -b * -t but to me that gives a different answer if b is 2 and t is 10 the former gives -20 and the latter +20
(you also divide two negatives and come up with a negative -100/-2 = -50 where i think that is 50)
Apologies if I’m wrong - its early Saturday and brain hasn’t been used in a while.
If I am right you need the guys to properly review and I need my money back…and/or a few free courses