First use distributive property on both sides of the equation. -9(-16 - f) = 4(1 - 3f) 144 + 9f = 4 - 12f Then isolate f on one side of the equation: 3f = -140 f = 46.67 --> (which is equal to -140/3) I'm sorry I couldn't help more. I don't know why it's wrong. Maybe try putting in it decial form instead.