Expalin how you knew wich symbol to use

Ten members of balin's soccer team ran warm ups for practice. each member ran the same distance. their combined distance was 5/6 of a mile. to find the distance that each member ran, balin wrote the expression below.

Binh says the point of intersections is (0,-3) which statements identify the errors binh made , check all that apply

Is a triangle with sides of length 6ft, 21 ft, 23 ft. a right triangle?