Answer is 17/49 spent on food
Step by step:
17/35 of her money is spent total
2/7 of 17/35 is spent on transport so
5/7 of 17/35 is spent on food
Solve
5/7 x 17/35 = food
Cross cancel as per attachment and multiply across
Answer is 17/49 spent on food
You can check your work
Add 17/49 food plus 2/7 transport = 17/35
Problem solved!