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The given slope of the stairs is rise / run = 7/10. Since the slope is given as a fraction, you can set up a simple proportion by equating the given slope with the desired rise over the unknown run (horizontal length).
7/10 = 2/x
where "x" is the horizontal length of the stairs.
Multiplying both sides by the common denominator 10x gives:
7x = 10(2)
7x = 20
Dividing both sides by 7 then gives:
x = 20/7 = 2.86 meters.
Rounding to the nearest meter gives a horizontal length of 3 meters.