200×(х+71)=54000 900×(16-с)=5400 400×(х-12)=3600

огромное спасибо

☺д

200 * (х + 71) = 54 000х + 71 = 54 000 : 200х + 71 = 270х = 270 - 71х = 199_____________200 * (199 + 71) = 54 000900 * (16 - с) = 540016 - с = 5400 : 90016 - с = 6с = 16 - 6с = 10___________900 * (16 - 10) = 5400400 * ( х - 12) = 3600х - 12 = 3600 : 400х - 12 = 9х = 9 + 12х = 21_________400 * (21 - 12) = 3600