Answer:
Her error was multiplying -3 and -4 which gives +12 but she wrote -12 instead
Explanation:
Mariana workings:
-3(2x - 4) = -12
-6x - 12 = -12
Her error was multiplying -3 and -4 which gives +12 but she wrote -12 instead
-6x = 0
x=0
Correct workings:
-3(2x - 4) = -12
-6x + 12 = - 12
-6x = -12 - 12
-6x = -24
x = -24/-6
x = 4