1

Problem

Find the value of y in (3y + 21)° and (6y - 12)°, which create a linear pair.

2

Step

Given angles

(3y + 21)° and (6y - 12)°

3

Step

The sum of a linear pair of angles is 180°

\$(3y + 21)°+ (6y - 12)° = 180°\$

4

Step

Combine like terms in the equation:

\$(9y - 9)° = 180°\$

\$9y = 180° - 9°\$

\$9y = 171°\$

5

Step

Divide both sides by 9 to solve for y:

\$y = (\cancel(171°))/(\cancel9)\$

\$y = 19°\$

6

Solution

So, the value of y is 19°.

7

Sumup

Please summarize steps

Choices

8

Choice-A

It is the correct answer because it satisfies the equation and makes the sum of the angles in the linear pair equal to 180°

Correct 19°

9

Choice-B

This option is incorrect. Substituting y = 18 does not satisfy 9y + 9 = 180

Wrong 18°

10

Choice-C

This option is incorrect. Substituting y = 13 does not satisfy 9y + 9 = 180

Wrong 13°

11

Choice-D

This option is incorrect. Substituting y = 10 does not satisfy 9y + 9 = 180

Wrong 10°

12

Answer

Option

A

13

Sumup

Please summarize choices