Answer:
50
Explanation:
Percantage Lin's family covered = 70 %
The distance they had travelled= 35 miles
The total distance of the trip = 70 / 100 x X = 35
( explanation : the formula to find the percentage of something is "percentage/ 100 of the total " so we used linear equation.... and so we made use of [this much percentage of "x" or something is this much] )
I hope you understood and this is right !