Aboat traveled 252 miles downstream and back the trip downstream took 12 hours the trip back took 84 hours what is the speed of the boat in still water what is the speed of the current

The way the problem is worded, I'm assuming the boat traveled 126 miles each way.
Velocity against the current 126 / 84 = 1.5 miles per hour
Velocity with the current 126 / 12 = 10.5 mph

"cs" means current speed
"bvs" means boat velocity in still water

bvs -cs = 1.5 mph
bvs +cs = 10.5 mph

Adding both equations
2 bvs = 12 mph
boat velocity in still water = 6 mph

and since
bvs +cs = 10.5 mph
then
6 + cs = 10.5
current speed = 4.5 mph

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