I really struggled with this. I still do not fully understand it.
(b) = ?
c = m – ( b x t )
bt = m – c
b = (m-c)/t
(m) = ?
c = m – ( b x t )
m = c + (bt)
(b) = ?, if m = 100, t = 120 and c = 0
0 = 100 – ( ? x 120)
? x 120 = 100 – 0
? = 100/120
**0.833r = burn rate (b)**
(m) = ?, if b =2, t = 120, c = 0
0 = ? – ( 2 x 120 )
? = 0 + (240)
**240 = max fuel (m)**