math
posted by Emily .
If Cathy walks for 2 h and rides her bicycle for 1 h, she can travel 36 km. If she walks for 2 h and rides her bicycle for 2 h, she can travel 56 km. How fast can she walk? How fast can she ride her bike? Let w represent walking and b represent biking.

2w + b = 36
2w + 2b = 56
well, since she walks 2 hours in each case, it is clear that the extra hour of biking gave her an extra 20 km.
b = 20
so, since 2w+20=36, w=8 
Thank you so much. I got really confused on the system of equations but I think I understand it now. Thank you :)

Glad to help. Translating words into symbols can be tricky, but the key is just to examine the data carefully. Believe it or not, it gets easier with practice, just like everything else.