The value of x in that equation is -12
Answer:
Step-by-step explanation:

Given
Area of the regular pentagon is 6.9 cm².
Find out the perimeter of a regular pentagon
To proof
Formula
Area of regular pentagon is

As given in the question
area of regular pentagon = 6.9 cm²
now equating the area value with the area formula.

Now put
√5 = 2.24 ( approx)
put in the above equation

thus
a² = 4.01
a = √ 4.01
a = 2.0 cm ( approx)
As perimeter represented the sum of all sides.
i.e regular pentagon have five sides of equal length.
Thus
perimeter of the regular pentagon = 5 × side length
= 5 ×2.00
therefore the perimeter of the regular pentagon = 10cm
option c is correct
Hence proved
13 + -6.6=6.4 all I did was subtract 6.4 by 13 and I got 6.6 but then turned it negative to solve the equation