Question 991904
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F=first number; S=second number=2F; T=third number=2S=4F
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F+S+T=91
F+2F+4F=91
7F=91
F=13
S=2F=2(13)=26
T=4F=4(13)=52
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ANSWER: The three numbers are 13, 26, and 52
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CHECK: 
F+S+T=91
13+26+52=91
91=91