Х+(х+7)+3×(х+7)=478 решите уравнение
X+(x+7)+3×3(x+7)=478 x+x+7+3x+21=478 5x+28=478 5x=450 x=90
X + x+ 7+ 3x+ 21 = 478 5x + 28 = 478 5x = 478-28 5x = 450 x = 450\5 x= 90