The Reading Railroad estimates its monthly maintenance costs on its railroad cars using the following equation: $Y=$$$870,000-$ $$25x,$ where the $x$ term stands for monthly track miles traveled. In March Reading's cars traveled $21,000$ miles. What is their estimate of maintenance costs in March?

Multiple Choice

$$345,000$

$$975,000$

$$1,395,000$

$$2,200,000$