Yang owed two credit cards with balances of $7,500 and $3,500. The card
with the $3,500 balance charged 1.4% more than the other. At the end of one
year, he paid is $797. What was the simple interest of each card?
If the rate on the 7500 balance is x, then
3500(x+0.014) + 7500x = 797
Now solve for x and finish it off