You're right, you don't understand because you keep wanting to apply your 'math' to mythical examples.

In the real world, this tax plan hurts the middle class.

 The current personal exemption grows with inflation while the new offered child credit does not.

The new plan would index the tax brackets for a slower gauge of inflation, which means that over time people would get pushed into higher tax brackets more quickly.

That's just a couple of the things you're not accounting for and the Republicans are counting on you not bothering to look beyond their 'talking point' carrot they dangle.

Behind that carrot is a big stick they plan to bring down on you.

Don't fall for the carrot.

Republicans didn't suddenly decide to look after your interests, like always they're out to sell you a bill of goods.