There is a 60% chance that a female will be chosen .
18/30 = 0.60 .
4m - 7n = 10
2m + 2n = 4 - multiply everything by -1.
4m - 7n = 10
-2m - 2n = -4 Add the 2 equations
(4m - 7n = 10)
+(-2m - 2n = -4)
-------------------------
2m - 9 n = 6.
The value of 2m - 9n would be 6.
The unknown side is part of the 90 degree angle, so it is not the hypotenuse.
Using the Pythagorean theorem:
x = sqrt(14^2 - 10^2)
x = sqrt(196-100)
x = sqrt(96)
x = 9.7979 ( round as needed)