Name: Justin
Who is asking: Student
Level: Secondary

Solve the following equations for x

  1. x+7=10

  2. x-7=10

  3. 3x=7

  4. x/3=10

  5. x/2+x/2=25

  6. 5x-2=3x+8

  7. 3(x+2)=4(x-1)

  8. x+3/2=2x-7/7+3

Hi Justin,

I like the "balance anology" for equations of this sort. In your first equation you have a balance with a "weight" of x+7 on one side and a "weight" of 10 on the other. The object is to manipulate the weights, without upsetting the balance, so that you end with only the variable x on one side and a number on the other, that is x=...

In the first problem

x + 7 = 10 if you subtract 7 from both sides, the balance is maintained and you get x + 7 - 7 = 10 - 7 or x = 3 You should now check to see that "x = 3" is correct. In the original equation, x + 7 = 10, substitute x = 3 to see if you really do have a balance. When x = 3 the left side of the equation is x + 7 = 3 + 7 = 10 which is the same as the right side and hence x = 3 is correct.

Now try the others. If you have trouble it might help to look at my solution to Kelley's problem.

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