25. The angles of a pentagon are [tex]\(x^{\circ}, 2x^{\circ}, (x + 60)^{\circ}, (x + 10)^{\circ}, (x - 10)^{\circ}\)[/tex]. Find the value of [tex]\(x\)[/tex].

(a) 40
(b) 60
(c) 75
(d) 80
(e) 90



Answer :

To solve for [tex]\( x \)[/tex] given that a pentagon has angles [tex]\( x^\circ, 2x^\circ, (x+60)^\circ, (x+10)^\circ \)[/tex], and [tex]\( (x-10)^\circ \)[/tex], we need to use the fact that the sum of the interior angles of a pentagon is always 540 degrees.

Step-by-step solution:

1. Identify the angles:
The angles given are:
- [tex]\( x \)[/tex]
- [tex]\( 2x \)[/tex]
- [tex]\( x + 60 \)[/tex]
- [tex]\( x + 10 \)[/tex]
- [tex]\( x - 10 \)[/tex]

2. Write the equation for the sum of the interior angles:
The sum of the interior angles of a pentagon is 540 degrees. Therefore, we can write the equation:
[tex]\[ x + 2x + (x + 60) + (x + 10) + (x - 10) = 540 \][/tex]

3. Combine like terms:
Combine all the terms involving [tex]\( x \)[/tex]:
[tex]\[ x + 2x + x + x + x + 60 + 10 - 10 = 540 \][/tex]
Simplify it further:
[tex]\[ 6x + 60 = 540 \][/tex]

4. Solve for [tex]\( x \)[/tex]:
Subtract 60 from both sides of the equation:
[tex]\[ 6x = 480 \][/tex]
Divide both sides by 6:
[tex]\[ x = 80 \][/tex]

So, the value of [tex]\( x \)[/tex] is [tex]\(\boxed{80}\)[/tex].