Fifteen years ago phil was twice as old as darell was then. three years from now darell will be as old as phil was four years ago. how old is phil now

29years

Step-by-step explanation:

let phil age now = x

15 years ago, phil age = x-15

let darell age now = y

15 years ago darell age = y-15

15 years ago,

phil's age = twice darell's age

x-15 = 2(y-15)

x-15 =2y-30

x-2y = -30+15

x-2y = -15 equation (1)

four years ago, Phil's age = x-4

three years from now, darell's age = y+3

x-4=y+3

x-y =3+4

x-y =7

x=7+yequation(2)

subtituting the value of x in equation (2) to equation (1)

x-2y = -15

7+y -2y = -15

7-y=-15

y=7+15=22

subtituting the value of y into equation (2)

x=7+y

=7+22=29

therefore, Phil age now is 29years

Assuming that the probability of boys and girls is equal (in reality slightly more boys than girls are born), the probability is 1/2, simply because the older girl's gender is given and therefore not a part of the probability.

This question comes from the 'boy or girl paradox', a.k.a. the Mrs Smith Problem.