How can i solve this equation?

Questions like these almost always warrant one step:

Isolate the variables (any term that has a letter associated with it; for example: x, d, m etc) from constants (plain numbers).

Keeping that in mind, put all the variables on the left hand side of the equation, and all the constants on the right hand side.

19-8d=d-17

∴ -8d **- d** = - 17 **- 19 **(when you take anything from the one side of the equation and put it on the another, the operation on that constant/variable changes as well. If it was 19 (positive 19) on one side, it becomes -19 on the other. This, of course, is the quick way of doing things. (For the mathematical explanation, refer to Roberto's answer).

∴ **- 9d** = **- 36**

Dividing by -9 on both sides, we would get

d = 4 (since -9 ÷ -9 = 1, and -36 ÷ 9 = 4)

Here's, really quickly, how to solve any other similar problems:

- Isolalte the variables from the constants by bringing all variables to one side and all constants to another.
- Perform the remaining operations, and you have your final answer!

Good luck solving other similar problems.