Final answer:
Sydney has biked 35 miles, which is 70% of her goal of 50 miles.
Step-by-step explanation:
To calculate the distance Sydney has biked as a percentage of her goal, we use her goal distance of 50 miles. Since she has completed 70% of her goal, we multiply 50 miles by 0.70 (which is the decimal form of 70%):
50 miles × 0.70 = 35 miles
Therefore, Sydney has biked 35 miles towards her goal.