John's weight bench can support 1000 pounds.  He wants to make sure to stay 20% under that weight for safety.  If he weighs 250 pounds how much weight can he put on the bar?
He wants to stay 1000*.2=<<1000*.2=200>>200 pounds under the max
So he wants to stay under 1000-200=<<1000-200=800>>800 pounds
That means he can put 800-250=<<800-250=550>>550 pounds on the bar
#### 550