Răspuns :
(x+34):21-9=40:10(x+34):21-9=4(x+34):21=4+9(x+34):21=13x+34=13 X 21x+34=273x=273-34x=239
[(x+34):21-9]·10=40⇒(x+34):21-9=40:10⇒(x+34):21-9=4⇒(x+34):21=4+9⇒(x+34):21=13⇒(x+34)=13·21⇒(x+34)=273⇒x=273-34⇒x=239