Find the length of the missing side. if necessary, round to the nearest tenth. 21.3 30 15 7.7 (it is a triangle and it has a right angle and you are looking for b and the numbers on the triangle are 16 [this is the longest side and slanted] and 14 [this is straight with no slant sorry couldnt upload a photo! ]

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)