Math question?

[Penn]

I am a bit hard headed in some area's, but also one that follows a question, this one I've taken apart several times, and still need to understand why my answer of .10c is incorrect.

What is a declarative statemen?

A declarative sentence (also know as a statement) makes a statement and ends with a period. It's named appropriately because it declares or states something. It might be more helpful, though, to think about what these kinds of sentences don't do. They don't ask questions, make commands, or make statements with emotion.

A bat and ball Cost $1.10.

The sentence states the cost of the bat and ball, declaring that the cost of a “bat and ball cost $1.10.

The second declarative statement

The bat cost one dollar more than the ball.

How much does the ball cost?