As shown in the figure, line BD equals one third AB equals one fourth CD, points m and N are the midpoint of line AB and CD respectively, and Mn equals 20 cm, so find the length of AC

1) Abdc sequence
BD = AB / 3, BD = CD / 4, that is: ab = 3bd, CD = 4bd
AB/2+CD/2+BD=MN
That is, 3bd / 2 + 4bd / 2 + BD = Mn = 20 = 9BD / 2
BD=40/9
So AB = 3bd = 120 / 9, CD = 160 / 9
AC=AB+BD+CD
=120/9+160/9+40/9
=320/9cm
It's hard to fight. I hope you can give me some points

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