Question 1124927
let the total weight of a packet be {{{m}}}

if the total weight of a packet is {{{(1/2)kg}}} more than {{{(4/5)}}} of its weight, we have:

{{{m=(4/5)m+(1/2)kg}}}

{{{m=2(4/(2*5))m+5(1/(5*2))kg}}}

{{{m=(8/10)m+(5/10)kg}}}.....both sides multiply by {{{10}}}

{{{10m=8m+5kg}}}

{{{10m-8m=5kg}}}

{{{2m=5kg}}}

{{{m=5kg/2}}}

{{{m=2.5kg}}}->the total weight of a packet


check:

{{{(4/5)}}} of it will be:

{{{(4/5)2.5kg=10kg/5=2kg}}} -> which is {{{(1/2)kg}}} less than {{{m=2.5kg}}}