Answers

1. The equation which can be used to find c is (D) 4(9 – c) = 2(9 + c).

   What is an equation?

   • An equation is a formula in mathematics that expresses the equality of two expressions by connecting them with the equals sign =.
   • A mathematical statement made up of two expressions joined by an equal sign is known as an equation.
   • 3x – 5 = 16 is an example of an equation.
   • We get the value of the variable x as x = 7 after solving this equation.

   To find the equation which can be used to find c:

   • Since Distance = Speed × Time.
   • Here c represents the speed of the current.
   • Thus, if the boat has a speed of 9 mph in still water.
   • Then its speed upstream = ( 9 – c ) mph.
   • Also, It takes the boat 4 hours to travel upstream.
   • Hence, total distance in upstream = 4 ( 9 – c ).
   • Similarly its speed in downstream = ( 9 + c ) mph.
   • Also, It takes the boat 2 hours to travel downstream.
   • Hence, total distance in downstream = 2 ( 9 + c ).
   • Since the distance upstream and downstream is equal.
   • ⇒ 4 ( 9 – c ) = 2 ( 9 + c )

   Therefore, the equation which can be used to find c is (D) 4(9-c)=2(9+c).

   Know more about equations here:

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   The correct question is given below:
   A boat has a speed of 9 miles per hour in calm water. it takes the boat 4 hours to travel upstream but only 2 hours to travel the same distance downstream. which equation can be used to find c, the speed of the current in miles per hour?

   (A) 2(9 – c) = 4(9 + c)

   (B) 9 + c = 4(9 – c)

   (C) 9 – c = 2(9 + c)

   (D) 4(9 – c) = 2(9 + c)

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