Hi there!
So here's what we know and what we are looking for. First, just to make things easier to understand, we'll replace "the distance they drove on the first day by "X" :
They drove 180 miles
180 = 1.5 × X
Now that you have your equation, all you need to do to find your answer is to isolate the "X" :
180 = 1.5 x X
divide each side of the equation by 1.5
120 = X
So your answer is : The parker family drove 120 miles on the first day.
There you go! I really hope this helped, if there's anything just let me know! :)