How do i find the area of a triangle with the side being 12

What is the value of x when x + 7 = 21?

Peyton's field hockey team wins 4 games out of every 7 games played. her team lost 9 games. how many games did peyton's team play?

Right triangle lmn has vertices l(7, –3), m(7, –8), and n(10, –8). the triangle is translated on the coordinate plane so the coordinates of l’ are (–1, 8). (x, y) → (x + 6, y – 5) (x, y) → (x – 6, y + 5) (x, y) → (x + 8, y – 11) (x, y) → (x – 8, y + 11)