Okay so ...
They drove a total of 920 miles right ?
But on the last day they drove 50 miles ...
What you do is subtract 50 from the total number of miles
920 - 50 = ....
The answer will show you how many miles left over aside from the 3rd day.
920 - 50 = 870
With the equation above you know for fact that in the first 2 days they drove a total of 870 miles on their trip.
The next step is to divide the remainder of miles ( 870 ) by 2 days
870 ÷ 2 = ?
Your answer will tell you how many miles they drove on each of the 1st two days...
870 ÷ 2 = 435
They drove 435 miles each on the first 2 days .
