5xD+4=_26
In Algebra, because we use x as a variable, we don't use x as a multiplication symbol.
Instead we use something like *; or we use the convention that if no arithmetic operator is shown between two numbers or variables multiplication is assumed (there is one exception to this rule and it causes much confusion and mistakes; so if you use mixed numbers put a + in the middle, or use improper fractions (preferred)).
So your equation should look like this:
5D + 4 = –26
The Golden Rule of Algebra is, "Do the same thing to both sides of an equation." When you do you will get another equation; i.e., you are guaranteed that the new left and right sides will have the same value.
Here we will subtract 4 from both sides:
5D + 4 = –26
– 4 = –4
–––––––––––
5D + 0 = –30
5D = –30
Now divide both sides by 5:
5D/5 = –30/5
D = –6
3/27/2014

Steve S.