This is Pythagorean's Theorem, with one leg being 10 and the hypotenuse being 16. Using those values in the theorem looks like this:

and

and

so

Take the square root of both sides to find that b = 12.5
Fraction simplified:33/40
Decimal:0.825
Percent:82.5
Answer: 14.73
Step-by-step explanation:
The given triangle is a right angle triangle.
EF^2 + DF^2 = ED^2
The hypotenuse is |ED| while the two shorter legs are |EF| and |DF|.
We can then apply the Pythagoras Theorem to find the length of EF.
(EF)^2 + (DF)^2 = (ED)^2
(EF)^2 + (12)^2 = (19)^2
(EF)^2 + 144 = 361
(EF)^2 = 361 - 144
(EF)^2 = 217
EF = 14.73
3(3x - 2)
Distribute (multiply) 2 inside the parentheses.
3 * 3x and 3 * -2
9x - 6