Answer:
12 bicycles
5 tricycles
Step-by-step explanation:
[tex]x + y = 17\\2x + 3y = 39\\\\2x + 2y = 34\\2x + 3y = 39\\\\y = 5\\\\2x + 2 * 5 = 34\\2x + 10 = 34\\2x = 24\\x = 12[/tex]