Question 723354
Bill has 2 plants that are known for growing an inch taller each year.
Let the plants be A and B.
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The total combined height of the plants is 81 inches.
A + B = 81
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42 years ago, one plant was twice the size as the other plant. 
How many years has he owned each plant?
A-42 = 2(B-42)
A-42 = 2B - 84
A - 2B = -42
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Solve the system of equations:
A + B = 81
A -2B = -42
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Subtract and solve for "B":
3B = 123
B = 41 inches
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Solve for "A":
A + B = 81
A + 41 = 81
A = 40 inches
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Cheers,
Stan H.