Hello!!!

Hope you are doing great!!!

As per the problem given,the data is as follows:

Given Workdone= 9800 Joules

Height = 10m

let,mass of person = M

Given mass of box = 20 kg

W=(m+M)gh

9800 = (20+M)*9.8*10

9800 = 98*(20+M)

100 = 20+M

M=100-20

M=80kg

Mass of the person = 80kg

Hope it helps!!!!!