Find number abc
If 925ab - 117bc = a0ac9 find number abc. Multiple solutions may exist.Correct answers: 2
#brainteasers #math
Railroad safetyIn 1870, Thomas S. Hall of Stamford, Conn., received a patent for the first automatic electric block railroad signal system in the U.S. (No. 103,875). When a train entered a block of track, Hall's electromagnetic device automatically set a signal when the locomotive struck a lever fastened to the rail. The signal was set to danger until the train cleared the block. After Hall invented the device in 1867, it was tried out on the New York and Harlem Railroad. |