Answer:
Well you can try to use a calculator, like the one on google. I can try to help if you really need it.
Step-by-step explanation:
w-(-3)=7
Pretend that there is a -1 in front of the bracket
w-1(-3)=7
Mutiply the bracket by -1
(-1)(-3)=3
w+3=7
Move +3 to the other side. Sign changes from +3 to -3.
w+3-3=7-3
w=4
Answer: w=4
Divide 309 by 3. You should get 103 (hamburgers). if you multiply that by 2 you will get 206 (cheeseburgers). Add the two together you get the total which was 309 originally.
103 hamburgers and 206 cheeseburgers.
