Part 1: you can find 4x-18 by dividing -18 by 4 to isolate the variable. The answer would be x= -4.5
Now that you know what x equals you can use that for the rest of your problems: BC is -4.5 + 12= 7.5, EF is 4× -4.5-18 = -36 and AD is 3×-4.5 = -13.5
BC= 7.5
EF= -36
AD= -13.5