a)MN =18+6/2 =24/2 =12cm
EF =18-6/2 =12/2 =6 cm
b)26+CD /2 =18
CD =2*19-26 =36-26 =10 cm
EF =26-10/2 =15/2 =8 cm
c) 6 =26-CD/2
CD =26-12 =14 cm
MN=26+14/2
MN =40/2 =20 cm
d)AB+CD/2 =22
AB+CD =44
AB-CD /2 =8
AB-CD=2*8 =16
AB+CD =44 -
AB-CD=16
--------------------
/ 2CD =28
CD =14 cm
AB=44-14 =30 cm