2(x+3)+5(x+1)=2*x+2*3+5*x+5*1=
=2x+6+5x+5=(2x+5x)+(6+5)=7x+11
А) 0,4(7х-2)-(1,6+1,7х) = 2,8х-0,8-1,6-1,7х=1,1х-2,4
б) 5х-(х-(-(3х-1)))=5х-х+3х-1=7х-1
BE = BD = 2x
CE = CF = 5x
AF = AD = 4
P = BE + BD + CE + CF + AF + AD
36 = 14x + 8
36 – 8 = 14x
x = 28 : 14 = 2
AB = 8 см.