The sum of the ages of Noah and Billy is 25; the sum of the ages of Noah and Ty is 20; and the sum of the ages of Billy and Ty is 31. Who is the oldest of the three and how old is he?

the oldest is Ty and his age is 24

Step-by-step explanation:

Let us assume the billy age be x

Noah age be y

And, Ty age be z

Now according to the question

y + x = 25 (1)

y + z = 20(2)

x + z  = 31(3)

z = 31 - x

since

y + z = 20

y + 31 - x = 20

y - x = -11 (4)

Now solve (1) and (4) equation

So,

y + x = 25

y - x = -11

2y = 36

y = 18

x = 25 - 18

= 7

z = 31-7

= 24

Hence, the oldest is Ty and his age is 24

the answer is a) y= 2 csc [0.5 (x+pi/2)]-1

step-by-step explanation: