Question

if an angle of a parllelogram is two- thirds of its adjacent angle then smallest angle of a parllelogram

Answer 1

let one angle= x
second angle = 2x/3
but sum of adjacent angles in a parallelogram= 180
x+2x/3=180
(3x+2x)/3=180
5x/3=180
x=(180*3)/5
x=36*3
x=108
one angle = x=108
adjacent angle= 2x/3=(2*108)/3
=72
Therefore
smallest angle=72

Answer 2

∠A=(2/3)∠B ⇒∠B=∠A÷(2/3)=(3/2)∠A
(1/2)∠A+(1/2)∠A+∠B=180
⇒∠A+∠B                    =180
⇒∠A+(3/2)∠A            =180
⇒(5/2)∠A                    =180
⇒        ∠A                    =180÷(5/2)
⇒        ∠A                    =  72
A student in grade 7, from Viet Nam