Question

a boy eats 25% of the cake and gives away 35% of it to his friends what percent of the cake is still left with him?

Answer 1

Percentage of cake ate by boy =25%
Percentage of cake he gave to his friend=35%
Therefore. Percentage of cake still left with him= 25% + 35% =60%
100% - 60% = 40%
Cake left with him is 40%

Answer 2

Answer:

Let us assume the full volume of the cake gift is 100 %

First he fare 25% of the cake.

Remaining Portion of cake once eating

=> 100% -25% =75%

Now he gifts thirty fifth of cake to the current friend.

So,

=> 75% -35% =40%

Hence  

the remaining portion of cake is 40%

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@GauravSaxena01