Think of PEMDAS. Solve in this order. Parentheses, Exponent, Multiply, Divide, Add, Subtract. Solving in this order will get you to the right answer. If you try to just solve from left to right, you may get it wrong if it is not solved in that order.
Answer:
7:4
Step-by-step explanation:
The total number of marbles is 9+12 =21
total marbles : green marbles
21 : 12
Divide each side by 3
21/3 : 12/3
7: 4
The answer to this question is 18, since E bisects angle CBD, you know that CBE is half of it, therefore you do 94(angle CBD) and split it in half which is 47. then you do 3x-7=47. add 7 to both sides which gets you 3x=54. then divide both sides by 3. which is x=18. I hope this helps!