Question 31424
To begin the equation you need to work what is in the parentheses first.  So what you get inside the parentheses is (20-15), Now you can solve what is inside the parentheses.  So now your equation should look like 42+ 14-(5).  Now you can get rid of the parentheses and you get 42+14-5.  Now you simplify the rest and you get 56-5=51.