Diane is mailing packages. Each small pack package costs her $2.10 to send. Each large package cost her $3.90. how much will it cost her to send 1 small package and 5 large package

First, organize your variables:

Let x = the number of small packages and y=the number of large packages. C = the cost of sending the packages.

Set up your equation:

2.10x+3.90y=C

Substitute 1 and 5 for x and y since that's how many packages Diane wants to mail, and then solve for C

2.10 (1) + 3.90 (5) = C

2.10+19.50=C

21.60=C

It will cost Diane $21.60