One Variable Equation Review

Question 1: Write an expression to model the difference between j and 7 times x.

Question 2: A reservoir has 25,000 gallons of water in it. The reservoir is being drained at a rate of 300 gallons per hour. Model this situation over x hours to find when the reservoir will be empty.

Question 3: The sides of an equilateral triangle are each 5x-4. If the total perimeter of the triangle is 78 meters, find the value of x.

Question 4: Jeff sells bracelets for $4 each. Each bracelet costs $1 to make and it costs Jeff $21 in materials before he can start making the bracelets. How many bracelets does Jeff need to make to break even?

Question 5: True or False: All you need to do to change a one-variable equation to a two-variable equation is replace one of the known values with an unknown value.