math 156
posted by debbie .
a pet shop has a total of 17 dogs and birds. Altogether there are 48 feet. How many dogs are ther and how many birds?

2b+4d=48 assuming dogs have four feet, birds two.
b+d=17
b=17d
2(17d)+4d=48
34+2d=48
d=7
b=10 
6.8