The fixer used 30/100*400 = <<30/100*400=120>>120 nails to fix the kitchen.
The number of nails remaining in the container after he fixes the kitchen is 400-120 = <<400-120=280>>280
He also uses 70/100*280 = <<70/100*280=196>>196 of the nails remaining in the container to fix the fence.
The total number of nails which the fixer hasn't used is 280-196 = <<280-196=84>>84
#### 84