d=David's age

2d-4=Jim's age

(2d-4)+3=John's age

d+(2d-4)+(2d-4)+3=35

5d-5=35

5d=40

d=8 David's age

2d-4=12=Jim's age

(2d-4)+3=15=John's age

Naruto U.

asked • 09/02/18John is 3 years older than jim.jim is 4 years less than twice david's age. How old are the three boys if their ages add up to 35.

Follow
•
2

Add comment

More

Report

d=David's age

2d-4=Jim's age

(2d-4)+3=John's age

d+(2d-4)+(2d-4)+3=35

5d-5=35

5d=40

d=8 David's age

2d-4=12=Jim's age

(2d-4)+3=15=John's age

We are looking for John and Jim's age

lets assign variables

I choose to use m for Jim's age, n for John's age, and d for David's age.

Now that we have variables we can write three equations

Because the sum of the ages is 35 we get (i) m + n + d = 35

John is 3 years older than Jim gives us (ii) n = m + 3

Jim is 4 years less than David, so m = d - 4 or (iii) d = m + 4

We have three equations in three unknowns, we want to get one equation in one unknown so we can solve it.

we can substitute into equation (i) the values of d and n expressed in terms of m

m + (m + 3) + (m + 4) = 35

now combine like terms and solve for Jim;s age (m)

once you find Jims age use equations (ii) and (iii) to find the other boys ages.

Ask a question for free

Get a free answer to a quick problem.

Most questions answered within 4 hours.

Find an Online Tutor Now

Choose an expert and meet online. No packages or subscriptions, pay only for the time you need.