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If the boy grows another 5 inches, he will be 1/2 as tall as his sister. HIs sister is 68 inch tall

Let sister = g, and boy = b

2b + 5 = g

g = 68

Plug in 68 for g

2b + 5 = 68

Isolate the b. Note the equal sign. What you do to one side, you do to the other. Do the opposite of PEMDAS.

first, subtract 5 from both sdies

2b + 5 (-5) = 68 (-5)

2b = 68 - 5

2b = 63

Isolate the b. Divide 2 from both sides

2b/2 = 63/2

b = 63/2

b = 31.5

The boy is 31.5 inches tall

hope this helps

Answer:

The height of boy is 29 inches.

Step-by-step explanation:

Given : If a boy grows 5 inches, he will be one-half as tall as his sister. His sister is 68 inches tall.

To find : How tall is the boy?  

Solution :

Let x be the boy's height and y be his sister's height.

We have given, His sister is 68 inches tall i.e. y=68 inches

Now,  If a boy grows 5 inches i.e. x+5

then he will be one-half as tall as his sister i.e. [tex]x+5=\frac{1}{2}y[/tex]

or  [tex]y=2x+10[/tex]

We know, y=68 substitute in above equation

[tex]68=2x+10[/tex]

[tex]2x=58[/tex]

[tex]x=\frac{58}{2}[/tex]

[tex]x=29[/tex]

Therefore, The height of boy is 29 inches.

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