base (50)F rule F (50)f[!(30)-F
][!(40)+F
]!F rule (x)f (1.5*x)f (1.25*x)f (1.7*x)f rule (x)- (x*1.2)- (x*0.8)- (x*1.05)- (x*1.0)- (x*0.95)- (x*0.87)- (x*1.12)- rule (x)+ (x*1.2)+ (x*0.8)+ (x*1.05)+ (x*1.0)+ (x*0.95)+ (x*0.87)+ (x*1.12)+