Who did the Columbian exchange hurt

How would having more railroad tracks be advantageous during a war

Montesquieu suggested dividing government into

Dominic and stacy each have a stamp collection. dominic has six fewer stamps than three times the number of stamps stacy has. dominic and stacy decide to give all of their stamps to their younger sister, mary. if stacy had s stamps, which expression represents the number of stamps that mary received? a. (3s − 18)(3s − 6) b. 2s − 18 c. 4s − 6 d. 4s − 18