His mass is 40.82
kg
From this formula
Weight = mass x the acceleration due to gravity
W=mg
Derive the formula to get mass of any object by multiplying both sides by 1/9
(1g)W=mg(1g)
Wg=m
m=Wg
where g as acceleration due to gravity equals to 9.8 ms^−2
Just substitute the given values as follows:
m=400newton9.8meter per second squared
=400kgms−29.8ms−2
m=40.82 kg
