Number of pieces of candy given away
Teresa had 15 pieces of candy, and then she gave away x pieces.
Now she has
15 - x pieces of candy
Maxwell had 25 pieces of candy, and then he gave away twice as Teresa, this is 2x.
Now he has
25 - 2x pieces of candy
We know that now they have the same number of pieces:
15 - x = 25 - 2x
We want to find the number of pieces Teresa gave away, this is x: we want to find x from the equation.
In order to find it we want to take all the terms with x to one side of the equation and all the numbers to the other side
15 - x = 25 - 2x
↓ taking -2x to the left side
15 - x + 2x = 25
↓ taking 15 to the right side
- x + 2x = 25 - 15
Now we simplify both sides of the equation:
-x + 2x = x
25 - 15 = 10
then
- x + 2x = 25 - 15
↓
x = 10
Then Teresa gave away
B. 10 pieces of candy
