A hot air balloon covered 2,100 miles in 7 days. If it covered 50 miles more each day than before, how many miles did it cover each day?

Here's a simple solution.

2100 miles in 7 days

2100/7=300 miles per day on average

there are 7 days so the 4th day is the middle day when the balloon traveled 300 miles

each day the balloon traveled 50 more miles

300, 350, 400, 450

300, 250, 200, 150

150, 200, 250, 300, 350, 400, 450 for days 1,2,3,4,5,6, and 7