Question

Quadrilateral QRST is a square. If the measure of angle RQT is 5x – 10. Find the value of x.

Answer 1

In a square, all four angles are equal to each other (90 degrees) and add up to 360 degrees.

So we can write this equation and solve for x.

4(5x - 10) = 360
   20x - 40 = 360
          20x = 400
          /20      /20
              x = 20

Therefore x = 20.

Let's check by substituting x into the angle and seeing if it does add up to 90 degrees like it is supposed to because it is a square.

    5x - 10 = 90
5(20) - 10 = 90
  100 - 10 = 90
           90 = 90

It is true so x = 20.

Answer 2

Every interior angle of square is a right angle (90°)

5x - 10 = 90
5x = 90 + 10
5x = 100
x = 100/5
x = 20