Question

if a boy grows 5 inches, he will be one-half as tall as his sister. His sister is 68 inches tall. How tall is the boy?

Answer 1

The height of boy is 29 inches.

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.
`x+5=(1)/(2)y`

or
`y=2x+10`

We know, y=68 substitute in above equation

`68=2x+10`

`2x=58`

`x=(58)/(2)`

`x=29`

Therefore, The height of boy is 29 inches.

Answer 2

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