P=suma toturor laturilor
a) P triunghiului=5,3+6,9+(x+0,4) b) Pdreptunghi=2(l+L )
=53/10+69/10+(10x+4)/10 P=2(19/4+(x-15/100) )
=126+10x P= 2( 19/4+x-15/100)
10x=126 P=2(475+100x-15)
x=126/10⇒x=12,65,3 P=2(460+100x)
PΔ= 5,3+6,9+12,6+0,4=25,2=25/10 P= 920+200x
=200x=-920
⇒x=-4,6=46/10