Final answer:
To solve the equation, combine like terms, isolate the variable, and perform the appropriate operations. The correct answer is (a) 5.
Step-by-step explanation:
To solve the equation 3x+(x+40)=60, you need to simplify the expression and isolate the variable.
Begin by combining like terms: 3x + x + 40 = 60.
This simplifies to 4x + 40 = 60.
Next, subtract 40 from both sides of the equation to get 4x = 20.
Finally, divide both sides by 4 to solve for x. x = 5, so the correct answer is (a).