Răspuns :
x - numarul necunoscut
(x+9,15):2=2x
x+9,15=2x·2
x+9,15=4x
9,15=4x-x
9,15=3x
x=9,15:3
x=3,05.
(x+9,15):2=2x
x+9,15=2x·2
x+9,15=4x
9,15=4x-x
9,15=3x
x=9,15:3
x=3,05.