You're close Dave.

"They say roses are red, violets are purple:
sugar is sweet and so is maple syruple.

I'm the seventh, out of seven sons:
my pappy was a pistol I'm a son-of-a-gun."

"Dang Me", by Roger Miller.

"Forget pounds and ounces, I'm figuring displacement!"

If we accept that: MBG(+)FGSF(=)HBG(F1)
And we surmise that: BG(>)HBG(F1) while GSF(<)HBG(F1)
Would it hold true that: HBG(F1)(+)AM500(x)q.d.(=)1.5lbGRWT?
PB answer: It depends.