Work Energy And Power

A person of weight \(70 \mathrm{~kg}\) wants to loose \(7 \mathrm{~kg}\) by going up and down \(12 \mathrm{~m}\) high stairs. Assume he burns twice as much fat while going up than going down. If \(1 \mathrm{~kg}\) of fat is burnt on expending 9000 k-cal. How many times must he go up and down to reduce his \(7 \mathrm{~kg}\) weight?

(Take \(g=10 \mathrm{~ms}^{-2}\))