Question 184330
let x=starting amount


"At the first he gives up 1/3 of his rice" ___ x-(1/3)x=(2/3)x remaining


"at the second he is allowed to keep 1/3 of what is left" ___ (1/3)*(2x/3)=2x/9 remaining


"at the third, he gives up 1/4 of what remains" ___ (2x/9)-(1/4)*(2x/9)=x/6 remaining


"After passing through all three customs stations, he has 6 pounds less than he started with"
___ x/6 = x-6


multiplying by 6 ___ x=6x-36


adding 36-x ___ 36=5x


dividing by 5 ___ 7.2=x