The correct first step in solving the equation is to apply the distributive property. Order of operations states to perform operations in this order, PEMDAS, left to right. Some operations can be applied at the same time left to right through the equation such as multiplication and division as well as addition and subtraction. Since 3 is being multiplied into parenthesis, this needs to be applied first using the distributive property.
3(x+8)=42
3*x + 3*8 = 42
3x + 24 = 42
You can continue to solve using inverse operations.
