name: Andrew,
Student

I am struggling with this problem: Could you please help me work out the value of x where: y = zx - x - c

thanks a lot

Andrew

Hi Andrew,

I am assuming that it is the lack of numbers in this problem that is causing you difficulties. I suggest that you replace z and c by numbers and see if you can solve the problem. Don't use the numbers 0, 1 or 2 but numbers like 3, 4, 5, ... I am going to let z = 3 and c = 7 and y = 5. Then the equation becomes

5 = 3x - x - 7. Solve for x.

What I see here is 3x - x which is 2x and hence

5 = 3x - x - 7

5 = 2x - 7 Now add 7 to both sides to get

5 + 7 = 2x - 7 + 7 or 12 = 2x and hence, dividing both sides by 2,

x = 6

Now can you mimic the steps I just went through but with z, c and y in the equation?

As before, what I see is zx - x which is (z - 1)x and hence

y = zx - x - c

y = (z - 1)x - c Now add c to both sides to get

y + c = (z - 1)x - c + c or y + c = (z - 1)x Finally, to find x, this time you need to divide both sides by (z - 1).

x = y + c/(z - 1)

Cheers,
Penny
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