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five years ago, john was twice peters age. peter is now x years old and john is now y years old.

a) write an equation to illustrate the relation between John's age and Peter's age five years age.

b) this year, the total of their ages is 28 years old. use this information to determine John's age in three years.

c) use substitution to justify that your answers to part (a) are correct.

please help

Respuesta :

Answer:

Step-by-step explanation:

a)

Peter now = x years old

John now = y years old

Five years ago

y-5 = 2(x-5)

y-5 = 2x-10

y = 2x-5

b)

x+y=28

y=28-x

Therefore

2x-5 = 28-x

3x = 33

x = 11

y = 28 - (11)

y = 17

Therefore

In three years time John will be:

17 + 3 = 20

c)

y-5 = 2x-10

Lefthand side:

(17)-5 = 12

Righthand side:

2(11)-10=22-10=12

Therefore 

Lefthand side =Righthand side

YAY!

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