Mark realizes that a lot of the friends on his friends list are people he doesn't talk to anymore.  He keeps 40% of his friends list and then contacts the rest.  Of those only 50% respond.  He removes everyone who did not respond.  If he had 100 friends how many does he have left after the removal?
Марк мефаҳмад, ки бисёре аз дӯстонаш дар рӯйхати дӯстонаш одамоне ҳастанд, ки дигар бо онҳо гап намезанад. Вай 40% аз рӯйхати дӯстонашро нигоҳ медорад ва сипас бо боқимондаҳо тамос мегирад. Аз онҳо танҳо 50% ҷавоб медиҳанд. Вай ҳамаи касонеро, ки ҷавоб надоданд, хориҷ мекунад. Агар ӯ 100 дӯст дошта бошад, пас пас аз хориҷ кардан чанд дӯст дорад?
How many friends did Mark contact? ** He contacted 1-.4=<<1-.4=.6>>.6 of his friends
How many friends did Mark contact? ** So he contacted 100*.6=<<100*.6=60>>60 people
How many friends does Mark remove? ** So he removes 60/2=<<60/2=30>>30 people
How many friends does Mark have left? ** So he has 100-30=<<100-30=70>>70 friends left
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How many friends did Mark contact? ** He contacted 1-.4=<<1-.4=.6>>.6 of his friends  
How many friends did Mark contact? ** So he contacted 100*.6=<<100*.6=60>>60 people  
How many friends does Mark remove? ** So he removes 60/2=<<60/2=30>>30 people  
How many friends does Mark have left? ** So he has 100-30=<<100-30=70>>70 friends left  
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