1) AMD= 5x/2
MBC= 3(8-x)/2
2) ABCD= 8(5+3)/2 = 32
DMC= ABCD-AMD-MBC
= 32-5x/2 -12 +3x/2
= 20 - x
4) f1(x)=5x/2 ; f2(x)=12-3x/2 ; f3(x)=20-x
f1(x)=f3(x)
5x/2=20-x
7x/2=20
x=40/7
f1(x)=f2(x)
5x/2=12-3x/2
4x=12
x=3
f2(x)=f3(x)
12-3x/2=20-x
x/2=-8 (impossible)
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