x = Bert's age
y = Jeff's age
z = John's age
Bert is twice as old as jeff mean:
x = 2 y
This is the same:
y = x / 2
John is 4 years younger than Bert mean:
z = x - 4
The sum of their ages is 31 mean:
x + y + z = 31
Now:
x + y + z = 31
x + x / 2 + x - 4 = 31
2 x / 2 + x / 2 + 2 x / 2 - 4 = 31
5 x / 2 - 4 = 31
Add 4 to both sides
5 x / 2 - 4 + 4 = 31 + 4
5 x / 2 = 35
Mutiply both sides by 2
5 x = 2 ∙ 35
5 x = 70
Divide both sides by 5
x = 70 / 5
x = 14
y = x / 2
y = 14 / 2
y = 7
z = x - 4
z = 14 - 4
z = 10
x = Bert's age = 14
y = Jeff's age = 7
z = John's age = 10
Bert is 14 yrs old.
bert is twice as old as jeff. John is 4 years younger than bert. The sum of their ages is 31. How old is bert?
2 answers
Jeff's age ---- x
Bert's age --- 2x
John's age --- 2x - 4
x + 2x + 2x-4 = 31
5x = 35
x = 7
so Bert is 14
Bert's age --- 2x
John's age --- 2x - 4
x + 2x + 2x-4 = 31
5x = 35
x = 7
so Bert is 14