Three girls on bike and 5 boys on bikes, are they older works? Think they were purchased in 1976...
Value?

Comparative works by the artist might give you an example of the possible value of them. You also might want to try a public library with books on art and prices as well as take them to an art gallery to see what they think.

I don't know the size of yours. Nor, do I know the age of them.

I did find the following which are examples of that artist's work on the following site 2004 AUCTION ITEMS (http://www.kennesaw.edu/arts/Benefit-2004/auction-items.html) and the price that they went for at the time.

087 “Music for Your Eyes” by G.R. Boulanger
Framed original lithograph, 22” x 22”. Value: $375.
Donated by: Regency Fine Art
Minimum bid: $300

088 “The Good Years” by G.R. Boulanger
Framed original lithograph, 21” x 23”. Value: $375.
Donated by: Regency Fine Art
Minimum Bid: $300

089 “Calendar Suite” by G.R. Boulanger
Framed original lithograph, 22” x 22”. Value: $480.
Donated by: Regency Fine Art
Minimum Bid: $384