To determine the answer, multiply the number of teeth Gear 1 hasD.and the number of revolutions it makes (R). Divide that number by the number of teeth Gear 2 hasD.to determine the number of revolutions Gear 2 makes (r). Because the gears are proportional, this formula will show you the ratio of teeth to revolutions.
r= DR/d
r= 250/15, or 1610/15, or 162/3

This problem does not have to be computed, because the two symbols cancel each other. The radical sign (\ ) in (\ 13):tells you to find the square root of 13. But the exponent (2) tells you to square the answer--that is, to multiply the square root of 13 by itself. This would get you back to 13.