Use order of operations: PEMDAS
Parenthesis
Exponent
Multiplication
Division
Addition
Subtraction
So multiply terms together where you can, then divide where you can, then add, and lastly, subtract.
Starting with M: 5x+10/x+4x/4x-10
D: 5x+10/x+4x/4x-10 ⇒ 5x+10/x+1-10
A: 5x+10/x+1-10
S: 5x+10/x+1-10
⇒ Altogether now our answer is: 5x+10/x-9