Which is the leading coefficient of the polynomial? 15x^4 -26x^3 -18x^6 - 19x^7

Expresa commuter train leaves downtown sation and travels at a average speed of 55 miles per hour towards the north side sation, which is 50miles away. thirty minutes later, express commuter train #7 leaves north side and travels at a average speed of 35miles per hour towards downtown sation. at the moment the two trains pass each other, how far(in miles) is train #12 from the downtown sation and how long(in minutes) has the #12 train been traveling

What is the answer to the question 5x+2x

Acompany makes steel lids that have a diameter of 13 inches. what is the area of each lid? round your answer to the nearest hundredth