Based upon your info, the length of the hypotenuse is 16 and that of one of the legs is 14. According to the Pythagorean Theorem, 14^2 + x^2 = 16^2. Thus, 196 + x^2 = 256, and x^2 = 60.
Take the square root of both sides, and remember that length is positive:
sqrt(x^2) = +sqrt(60)
= +2sqrt(15)
= 7.746
= 7.7 (rounded to the nearest tenth)