22.-------- 6x4=2424:(0,3x0,3)=266,(6) placi ≈267 placi
80 placi......5 sparte266,(6)placi.....x spartex=267×5/80=16,(6)≈17 placi
267 +17=284 placi
23-------------- Adr.=L·l
=47m·21m
=987
A patr.=
=50cm·50cm
=2500
987=9870000
9870000:2500=3948 (placi)