Hello I need help on this question!

5

Step-by-step explanation:

Refer to attachment for marking of sides.

In the given figure , ∆ABC , ∆ABD and ∆ADC are right angled triangles . Therefore here we can use the Pythagoras theorem , as ,

base² + perpendicular² = hypotenuse ² .

• In ∆ABD , we have ;

AB² + BD² = AD²

AB² + x² = 10²

AB² = 10² - x²

AB² = 100 - x²

• Again in ∆ADC , we have ;

AC² + AD² = CD²

AC² = 20² - 10²

AC² = 400 - 100

AC² = 300

Again in ∆ABC , we have ,

AC² = AB² + BC²

Substituting the values from above ,

300 = 100-x² + (20-x)²

300 = 100 - x² + 400 + x² - 40x

40x = 500 - 300

40x = 200

x = 200/40

x = 5

Hence the required answer is 5 .

Letter c i’d say

It's like discovering the answer to a puzzle. the purpose in solving an equation is to find the value or values of the variable that makes it a true statement. any value of the variable that makes the equation true is called a solution to the equation.