Answer: " y = 30° " . _____________________________________ Note: The sum total of the measure of all angles lying on a straight line is 180°.
So; x + y + z = 180 .
Given: x = 2y ; z = 3y ; __________________ Find the value of: " y " ; _______________________ Since: x + y + z = 180 ;
Substitute: "2y" for "x" ; and: "3y" for "z" ; _______________________ 2y + y + 3y = 180 ;
6y = 180 ; ______________________ Divide EACH SIDE of the equation by "6" ; to isolate "y" on one side of the equation; and to solve for "y" ; ___________________________ 6y/ 6 = 180 / 6 ;
y = 30 ; ____________________________ Let us check our work; ____________________________ 2y + y + 3y = 180 ;
Substitute our solved value: "30" ; for "y" ; in the equation; to see if the equation holds true: ____________________________ 2(30) + 30 + 3(30) =? 180 ? ____________________________ 60 + 30 + 90 = ? 180 ? ____________________________ 90 + 90 = ? 180 ? Yes! ____________________________
