[tex]\it b:9:3\cdot2\cdot5=30 \Rightarrow b:27\cdot10=30|_{:10} \Rightarrow b:27=3 \Rightarrow b=3\cdot27=81[/tex]
Explicație pas cu pas:
b:9×3×2=30:5
b:9×3×2=6
b:9×3=6:2
b:9×3=3
b:9=3:3
b:9=1
b=9×1
b=9
72:b:4×5=60:6
72:b:4×5=10
72:b:4=10:5
72:b:4=5
72:b=5×4
72:b=20
b=72:20
b=3,6
