What number is that, to which if 1, 5, and 13, be severally added, the first sum shall be to the second, as the second to the third? Select the correct option.
A) 1 B) 2 C) 3 D) 4 E) 5
Solution   Let x= the number required.   By the conditions, x+1:x+5 = a+5:x+13   Subtracting terms, (Art. 385,2.) x+1:4 = x+5:8   Therefore 8x+8 = 4x+20. And x = 3.   Answer 3
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What number is that, to which if 1, 5, and 13, be severally added, the first sum shall be to the second, as the second to the third?