Age Problem.. ^_^

Algebra Level 1

The sum of the ages of Dave and Ted is 48 years. Eight years from now, Ted will be three times Dave's age. Find their present age.

Ted: 28; Dave: 20 Ted: 40; Dave: 8 Ted: 7; Dave: 41 Ted: 30; Dave: 18

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6 solutions

Mohammad Khaza
Jul 22, 2017

Sum of ages now=48

In 8 years, sum of ages will be =48+16=64

as Ted will be 3 times as old as Dave.that means their age's ratio will be =3:1

now, 64 4 \frac{64}{4} = 16 16

so, Teds age will be = 16 × 3 16 \times 3 = 48 48 and Daves age will be = 16 × 1 16 \times 1 = 16 16 years old

so, current age of Ted is = 48 8 48-8 = 40 40 years old and current age of Dave is= 16 8 16-8 = 8 8 years old

Michael Lee
Dec 21, 2014

Sum of ages now=48 In 8 years, sum of ages=48+16=64 Ages such that Dave is three times the age of Ted. Ted=16, Dave=48. But this is our answer for 8 years in the future so Ted current age=8, Dave current age=40

D = p r e s e n t a g e o f D a v e D=present~age~of~Dave

T = p r e s e n t a g e o f T e d T=present~age~of~Ted

At present: D + T = 48 D+T=48 \implies T = 48 D T=48-D ( 1 ) \color{#D61F06}(1)

Eight years from now: T + 8 = 3 ( D + 8 ) T+8=3(D+8) ( 2 ) \color{#D61F06}(2)

Substitute ( 1 ) \color{#D61F06}(1) in ( 2 ) \color{#D61F06}(2) ,

48 D + 8 = 3 D + 24 48-D+8=3D+24 \implies 56 = 4 D + 24 56=4D+24 \implies 4 D = 56 24 4D=56-24 \implies D = 8 \color{#3D99F6}\boxed{D=8}

It follows that,

T = 48 8 T=48-8 \implies T = 40 \color{#3D99F6}\boxed{T=40}

Chelsea Long
Jul 31, 2015

D=Dave's age, T=Ted's age

D+T=48, and T+8=3(D+8), which then becomes T+8=3D+24 If we solve the 2nd equation for T, we get T=3D+24-8, or T=3D+16

If we use this value to substitute T in the 1st equation, we get: D+(3D+16)=48 4D+16=48 4D=48-16 4D=32 D=32/4 D=8

This means that Dave is 8, so now we can solve for T, using: D+T=48 8+T=48 T=48-8 T=40

So Ted is 40, and Dave is 8.

Jack Rawlin
Dec 22, 2014

Have t = T e d t = Ted and d = D a v e d = Dave

From the information given we can obtain two equations

  1. t + d = 48 t+d = 48

  2. t + 8 = 3 ( d + 8 ) t+8 = 3(d+8)

Re-arranging both equations to get two equations for t t gives us

  1. t + d = 48 t = 48 d t+d = 48 \Rightarrow t = 48 - d

  2. t + 8 = 3 ( d + 8 ) t = 3 ( d + 8 ) 8 t = 3 d + 16 t + 8 = 3(d + 8) \Rightarrow t = 3(d + 8) - 8 \Rightarrow t = 3d + 16

Using simultaneous equations gives us

48 d = 3 d + 16 48 - d = 3d + 16

Simplifying this gives us a value for d d

48 d = 3 d + 16 32 d = 3 d 32 = 4 d d = 8 48 - d = 3d + 16 \Rightarrow 32 - d = 3d \Rightarrow 32 = 4d \Rightarrow d = 8

Now that we have a value for d d we can now work out a value for t t

t = 48 d t = 48 ( 8 ) = 40 t = 48 - d \Rightarrow t = 48 - (8) = 40

So t = 40 t = 40 and d = 8 d = 8

Christian Daang
Oct 12, 2014

Let: x = age of ted 48-x = age of dave

Therefore,

x+8 = 3(48-x+8) x+8 = 3(56-x) x+8 = 168-3x 4x = 160 x = 40

Then,

Age of ted is 40 years old and 8 years old is the age of dave...

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