If Pat borrows $10,000 to buy a car, for 3 years at 7% interest, the total interest is $2,100. What is the total cost of the car? O $12,200
O $10,000
O $12,100
O $17,000

17,0000 is the answer

Well, if x + y = 3500, we can subtract y from both sides to give us x = 3500 - y. We can substitute that into the second equation:
x - y = 2342
(3500-y) -y = 2342
3500 - 2y = 2342
-2y = 2342-3500 = -1158
2y = 1158
y = 579
And substitute y back into the first equation:
x + y = 3500
x + 579 = 3500
x = 3500-579= 2921

So he has 2,921 contemporary titles. You can substituted the values back into the original equations to check them. Make sense?