The equation for this problem would be 56=2x+5x, which can be simplified to 56=7x, x being the number of cups of soda. To find x you must get it alon be dividing both sides by 7 (56/7=7x/7). Doing this gives you 8=x, or in other words 8 cups of soda.
Hope this helps!
You can switch the addition and subtraction signs to get q-(+5) =? So you want to find what 5 can be subtracted from to get 3, which is 8. 8+(-5) =3
