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Diego's sister is twice his age minus 9 years. She is also as old as half the sum of the ages of Diego and both of his 12-year-old twin brothers. Write and solve an equation to find the ages of Diego and his sister.

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Answer:

Diego is 14 years old.

Sister is 19

Step-by-step explanation:

x = Diego's age

x + 24

2x-9 = 2

First to get rid of the fraction we multiply each side by 2

2(2x-9) = 2((x+24)/2)

4x-18 = x+24

The we isolate x

4x-18 = x+24

-x+18 -x+18

3x = 42 Now we divide each side 3

3 3

x = 14

So Diego is 14

Now we can solve for his sister. We can use one of the two equations from earlier to do this.

Plug 14 in for x and then solve for his sister

2(14)-9

28-9

19

His sister is 19

Answer:

Diego's age is 14 years.

His sister's age is 19 years.

Step-by-step explanation:

Let d represent Diego's age.

We have been given that Diego's sister is twice his age minus 9 years.

The age of Diego's sister would be [tex]2x-9[/tex].  

We are also told that she is also as old as half the sum of the ages of Diego and both of his 12-year-old twin brothers. We can represent this information in an equation as:          

[tex]2x-9=\frac{x+12+12}{2}[/tex]

Let us solve for x:

[tex]2x-9+9=\frac{x+24}{2}+9[/tex]

[tex]2x=\frac{x+24}{2}+\frac{2*9}{2}[/tex]

[tex]2x=\frac{x+24}{2}+\frac{18}{2}[/tex]

[tex]2x=\frac{x+24+18}{2}[/tex]

[tex]2x=\frac{x+42}{2}[/tex]

[tex]2*2x=\frac{x+42}{2}*2[/tex]

[tex]4x=x+42[/tex]

[tex]4x-x=x-x+42[/tex]

[tex]3x=42[/tex]

[tex]\frac{3x}{3}=\frac{42}{3}[/tex]

[tex]x=14[/tex]

Therefore, Diego's age is 14 years.

[tex]\text{His sister's age}=2x-9[/tex]

[tex]\text{His sister's age}=2(14)-9[/tex]

[tex]\text{His sister's age}=28-9[/tex]

[tex]\text{His sister's age}=19[/tex]

Therefore, his sister's age is 19 years.