I feel like im useless/worthless pice of sh*it rn

The verbal translation for the difference of m and 7 increased by 15

Extra points! find the missing dimension! need asap

Will mark 50 show all what is the solution to the system of equations? use the substitution method and show your work. -5x+y= -3 -15 x+3y=7 explain what your answer in part (a) tells you about the association of the lines in this system.