Melanie has decided to run for president of her science club. She would like to purchase colorful rubber bracelets that say, "Melanie for President!" She plans to pass meeting. There are twenty bracelets in each package. Each bracelet costs $3.50. How much will Melanie have to pay if she purchases two packages of colorful bracelets?

Melanie wants to buy two packages of bracelets, so she will have 2 x 20 = <<2*20=40>>40 bracelets.

If each bracelet costs $3.50, then Melanie will have to pay 40 x $3.50 = $<<40*3.5=140>>140. Answer: \boxed{140}.