What is the name of the relationship between one angle and eight angle

"The straight lines which form right angles are called perpendicular. Euclid uses right angles in definitions 11 and 12 to define acute angles (those smaller than a right angle) and obtuse angles (those greater than a right angle). Two angles are called complementary if their sum is a right angle."

SOURCE:WIKI.COM

HARD TO TELL WHAT YOU ARE TALKING ABOUT BUT IS THIS IT??

Problem one:

let the variable be x:

• apply division property of equality:

Problem two:

let the variable be y

• apply division property of equality: