A ball and a bat cost $110 total. The bat costs $100 more than the ball. How much does the ball cost?

For this system of equation,
I designated x for the ball and y for the bat. I know that both equal to 110.
So I wrote the first equation as
x+y=110
I don't know how to proceed for the second equation.

Since the ball is less than the bat, would it be subtracted?

Do it with one variable:

cost of ball ---- x
cost of bat = x + 100

x + x + 100 = 110
2x = 10
x = 5

ball costs $5, bat costs $105

your way:
x+y = 110
y - x = 100
Add them: 2y = 210
y = 105
sub back into the first and do it mentally, x = 5

To determine the second equation, you need to use the information given about the cost of the bat being $100 more than the ball.

Let's assign x for the cost of the ball. Since the cost of the bat is $100 more than the ball, the cost of the bat can be represented as (x + $100).

So, the second equation can be written as:

x + (x + $100) = $110

Now, you can simplify the equation by combining like terms:

2x + $100 = $110

To isolate 2x, you can subtract $100 from both sides of the equation:

2x = $110 - $100

2x = $10

Finally, divide both sides of the equation by 2 to solve for x:

x = $10 / 2

x = $5

Therefore, the ball costs $5.