I dont understand this??

ZY = 23

Step-by-step explanation:

Given in the picture:

ZY = 7a + 2

       ZD = DX, diagonals of parallelograms bisect each-other so

3(2a+1) = 9a -6 , given in the picture

  6a +3 = 9a - 6, subtract 9a and 3 from both sides

 6a -9a = -6 -3, combine like terms

      -3a = -9, divide both sides by -3

         a = 3

ZY = 7a + 2

ZY = 7·3 + 2

ZY = 23

step-by-step explanation:

we are given

since, we have to isolate x on anyone side

so, we can move all x terms on one side

subtract both sides by 2x

add both sides by 9

divide both sides by 4

we get

80x^8−68x^6+16^5−20x^4−4x^3+8x^2

hope i'm right lol