John found that the perimeter of a square is 4x + 21ft. If the perimeter's length is 100 ft what is the value of x ?

Answer 1

The perimeter of a square can be calculated using the formula:

\[ P = 4s \]

where \( s \) is the length of one side of the square.

In this case, we have the perimeter given as:

\[ P = 4x + 21 , \text{ft} \]

We also know that the perimeter equals 100 ft. Therefore, we can set up the equation:

\[ 4x + 21 = 100 \]

To solve for \( x \), we first subtract 21 from both sides of the equation:

\[ 4x = 100 - 21 \] \[ 4x = 79 \]

Next, we divide both sides by 4:

\[ x = \frac{79}{4} \] \[ x = 19.75 \]

Thus, the value of \( x \) is \( \boxed{19.75} \).