Use scientific notation to express the diameter of a red blood cell that measures 0.00075. HURRYYY!!! a. 7.5 x 10^-3

b. 7.5 x 10^-4

c. 7.5 x 10^3

d.7.5 x 10^4

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.