3x+7=13 (x=-2; x=2; x=5)

3x + 7 = 13

3x = 13 - 7

3x = 6

x = 6:3

x = 2

There are two sites of every equation. The sign = means that the two sites are equal.

So, we know that 3x+7 is equal as 13. 3x+7=13

In order to find the unknown x we should rewrite the equation such that on one site we have only x and on the other all left

3x=13-7 ("+"is "-" on the other site of the equation)

3x=6

x multiplied with 3 gives 6, so we need to divide 6 with 3 in order to get the value of x.

x=6/3=2