王东家承包了两块三角形土地△ABC和△A'B'C',已知A'B'分之AB=B'C'分之BC=A'C'分之AC=3分之4,

三角形ABC的周长是240米------> AB + BC + AB = 240
AB/A'B' = BC/B'C' = AC/A'C' = 4/3 -------> AB=4/3 * A'B' ,BC = 4/3 * B'C',AC = 4/3 *A'C'
------> A'B' = 3/4 * AB,B'C' = 3/4 * BC,A'C' = 3/4 *AC
------> A'B' + B'C' + A'C' = 3/4 * AB + 3/4 * BC + 3/4 *AC
--------------------------- > = 3/4 * (AB + BC + AB)
---------------------------> = 3/4 * 240
---------------------------> 180(m)

AB=3/2A'B',
BC=3/2B'C',
AC=3/2C'A'
AB+BC+AC=3/2(A'B'+B'C'+C'A')=36