5/7 и 1/2= 5/7(*2) и 1/2(*7) = 10/14 и 7/14
7/20 и 1/15 = 7/20(*3) и 1/15(*4) = 21/60 и 4/60
5/26 и 5/39 = 5/26(*3) и 5/39(*2) = 15/78 и 10/78
8/11 и 5/8 = 8/11(*8) и 5/8(*11) = 64/88 и 55/88
6/14 - велосипед
5/14 - смартфон
разница - 1/14=280 руб
заработал 14/14, т е 280*14 =3920
Х-(-8)=13
х+8=13
х=13-8
х=5
Ответ: х=5
-3.4х-346.8=-68
-3.4х=-68+346.8
-3.4х= -278.8
х=82