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Work Shown:
1 km = 1000 m
3.5 km = 3500 m ............. multiplying both sides by 3.5
(70 paces)/(50 m) = (x paces)/(3500 m)
70/50 = x/3500
7/5 = x/3500
7*3500 = 5x .............. cross multiply
5x = 7*3500
x = (7*3500)/5
x = (7*5*700)/5
x = 7*700
x = 4900
Ann takes 4900 paces to walk 3.5 km