Compare unit rates. The first one is filling at the rate of (5/8 gal) / (42 minutes) = 0.01488 gal/min (rounded). The second one fills at the rate of (5/9 gal) / (40 min) = 0.0139 gal/min (rounded). The first unit rate is greater than the second one. The first one is taking on fluid faster, but we can't say anything about "filling", because we don't know how much each tank holds, or how much may have already been in one or the other before all of this filling and running and pouring started .... I gotta go.