For this problem, they have given you most of the information you need. You have an equation and you have a point on the graph. All you have to do it plug the x and y values that they gave you into the equation and solve for c. We know x=0 and y=5 so we get 3(0)-c=2(5). Remembering order of operations, you need to multiply next which will give you 0-c=10. In order to make c positive you can multiply by -1 and the result is c=-10 :)

You do not "make c positive" by multiplying by negative one. Instead you find the value of c by doing that operation on both sides of the equation. Indeed, as shown by this correct result, c equals -10, and is therefore not made into anything. What Kimberly probably meant to say is that we are not interested in finding the value of -c, so we must multiply (or divide) by -1 to obtain the value of c.

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