86+х+14=х+86+14=х+(86+14)=х+100
74+а+13=а+74+13=а+(74+13)=а+87
с+82+14=с+82+14=а+(82+14)=а+96
41+28+а=а+41+28=а+(41+28)=а+69
(318+х)-209=(318-209)+х=109+х
(436+у)-186=(436-186)+у=250+у
х-187+379=(х+379)-187=х+(379-187)=х+192
а-426+550=(а+550)-426=а+(550-426)=а+124