PLZZZ HELP WILL MARK BRAINLIEST PLUS 25 POINTS

What is the value of 1/3x + 7x when x = 5

Ze trinomial x2 + bx – c has factors of (x + m)(x – n), where m, n, and b are positive. what is ze relationship between the values of m and n? explain how you got ze answer

Abarge can safely haul no more than 400 tons across the river. the barge has an empty weight of 24 tons. the average weight of the railroad cars is 4 tons each.bhow many railroad cars can the barge haul?