80N * 50 hours = 4000 N*hrs

N*h would be newtons per hours !!

you would then have 4000N * 50 hours !!!

Ns would be newtons per second !!

you would then have 4000N * 1 seconds !!!

which would be correct if you used 4000N in 1 second

but you didnt you used the 4000N in 50 seconds

time is in a newton already

if I write that 1 newton is the force required to accelerate a 1kg mass to a acceleration rate of 1m/s/s

I already know that it will accelerate the 1 kg mass to an acceleration rate of 1m/s/s in 1 second because time is already there in the newton.

a newton unit of force is a combination of time , mass , distance , acceleration all whipped up into a single unit...

Either is acceptable, but one could convert between them easily enough.

Neither is acceptable.

otherwise the description of 1 newton would be

1Ns is the amount of force applied to a mass of 1kg to accelerate the 1kg mass to an acceleration rate of 1m/s/s