Jolene and Phil have four children, each with the same birthday.  They gave birth to their first child exactly 15 years ago.  They gave birth to their second child exactly one year after the birth of their first child.  They gave birth to their third child on the fourth birthday of their second child. Two years after the birth of their third child, they gave birth to their fourth child.  How old, in years, is their fourth child?
Ҷолин ва Фил чор фарзанд доранд, ҳар кадом бо рӯзи таваллуди яксон. Онҳо даҳ сол пеш фарзанди аввалини худро таваллуд карданд. Онҳо даҳ сол пас фарзанди дуввумро, даҳ сол пас аз таваллуди фарзанди аввалини худ, таваллуд карданд. Онҳо фарзанди сеюми худро дар рӯзи таваллуди чорумини фарзанди дуввум таваллуд карданд. Ду сол пас аз таваллуди фарзанди сеюми худ, онҳо фарзанди чоруми худро таваллуд карданд. Фарзанди чоруми онҳо чандсола аст?
How old is their first child? ** Their 1st child was born 15 years ago, and therefore is <<15=15>>15 years old.
How old is their second child? ** Their 2nd child was born 1 year after their 15-year-old child, and therefore is 15-1=<<15-1=14>>14 years old.
How old is their third child? ** Their 3rd child was born 4 years after their 14-year-old child, and therefore is 14-4=10 years old.
How old is their fourth child? ** Their 4th child was born 2 years after their 10-year-old child, and therefore is 10-2=8 years old.
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How old is their first child? ** Духтари аввалини онҳо 15 сол пеш таваллуд шудааст, ва бинобар ин, ӯ <<15=15>>15 сол дорад.  
How old is their second child? ** Духтари дуюми онҳо 1 сол пас аз духтари 15-солаи онҳо таваллуд шудааст, ва бинобар ин, ӯ 15-1=<<15-1=14>>14 сол дорад.  
How old is their third child? ** Духтари сеюми онҳо 4 сол пас аз духтари 14-солаи онҳо таваллуд шудааст, ва бинобар ин, ӯ 14-4=10 сол дорад.  
How old is their fourth child? ** Духтари чоруми онҳо 2 сол пас аз духтари 10-солаи онҳо таваллуд шудааст, ва бинобар ин, ӯ 10-2=8 сол дорад.  
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