Hey there!
ASSUMING!
-3/7m = 12
IF SO!
DIVIDE -7/3 to BOTH SIDES
-7/3 * -3/7m = 12 * 7/3
CANCEL out: -7/3 * (-3/7) because it give you 1
KEEP: 12 * (-7/3) because it give you the m-value
NEW EQUATION: m = 12 * (-7/3)
SIMPLIFY IT!
m = -28
Therefore, your answer is: m = -28
(Option A)
Good luck on your assignment & enjoy your day!
~Amphitrite1040:)