Fuel consumption VS Distance + Speed change

[QAMER]

Hi ,Here is another one . I tried to solve it by fuel consume /mile x fuel consume for 2nd part of trip,did not work.

Your ship has steamed 2061 miles at 24 knots using 850 tons of fuel oil. The distance remaining to your next port is 1645 miles. If you decrease speed to 19 knots, how much fuel will be used to reach that port?
A 425 tons
B 537 tons
C 625 tons
D 712 tons

Thanks

[Sébastien]

Again, Reed's volume 4 chapter 7
General expression for voyage consumption
new cons/old cons = (new displ/old displ)exp 2/3 x (new speed/old speed)2 x (new dist/old dist)
new cons = 850 x 1 x (19/24)2 x (1645/2061) = 850 x 0.6267361 x 0.7981562 = 425 tons
Answer is A