3x - 9 + 7x - 10 = 9x - 5x + 5
Start off by combining like terms.
Let's do the left side first: 3x + 7x = 10x and -9 - 10 = -19
Now do the right side: 9x - 5x - 4x and 5 is left over.
Your equation now should look like this: 10x - 19 = 4x + 5
Next step: subtract 4x from both sides
10x - 19 = 4x + 5
-4x -4x
6x - 19 = 5
Now add 19 to both sides.
6x - 19 = 5
+19 +19
6x = 24
divide 6x and 24 by 6
6x/6 = 24/6
x = 4