Question

A vendor sells 70 of the oranges he had and throws away 20% of the remainder.Next day he sells 50% of the remainder and throws away the rest.What % of this oranges does he throw away

Answer 1

vendor has 70 oranges, he throws 20% i.e 14 oranges . remaining oranges 70-14=56 . next day he throws 50% i.e 28 .remainig oranges =26.% of oranges he throw =42/70*100=60% the % oof orange he does not throw=40% 

Answer 2

The first sentence is not very clear to me...  whether he sells 70  or  the total number is 70.
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Total number of oranges he had = N
Thrown away = (N  - 70)*20/100 = (N-70)* 1/5
Remaining = (N-70) * 4/5

Sold next day = (N-70) * 4/5 * 1/2
Thrown away now = (N-70) *4/5 *1/2 = (N-70)*2/5

Total thrown away oranges = (N-70) * (1/5+2/5) = (N-70) * 3/5

Percentage of thrown away fruits = (3 N /5 N - 42 / N ) * 100
                       = 60 -  4200/N

For example, the oranges are totally 140, then  the percentage is  30 %