Find number abc
If 614cb - 54c44 = a1a6 find number abc. Multiple solutions may exist.Correct answers: 3
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Gas maskIn 1850, the first U.S. patent No. 7,476 for a gas mask with a self-contained breathing apparatus was issued to Benjamin J. Lane of Cambridge, Mass. for a "respiring apparatus." (The first U.S. patent for an "inhaler or lung protector" resembling a gas mask of the modern type was awarded to Lewis Phectic Haslett of Louisville, Ky., on 12 Jun 1849. It had a filter of woolen fabric or other porous substance to purify the air and remove dust.) |