No, you'll do 10% more work, and you'll make 1% less money.
Let's imagine that he cut your hourly rate in half, and doubled your hours. Then you would be doing twice as much work, for exactly the same money.
He told you right at the beginning what he's doing, where he said he needs to cut your pay. Right there, you knew that he's not going to offer you any way to make the same amount of money.
What he offered you is a way for him to get <em>more</em> work done, in return for slightly <em>less</em> money. And from YOUR point of view ... you spend 10% more time on the job, you get home 10% later, you're 10% more tired, you have 10% less time for homework, and you <u>lose</u> a penny of every dollar that you're making now.
The boss is a scheming rat for concocting such a deal. If you take it, you're being screwed three ways.
Don't let him tell you that he's doing you a favor, and you should be grateful to him for the job. He is a businessman, and you should act like one too. You have a product that you're willing to sell, for a fair price. Your product is your work. The boss needs your product.
Back when you first started working for him, the two of you agreed on a price for your product. There's no good reason that he should expect to keep getting the same product, but at a new reduced price.
Remember when you started that job. That was a time when he didn't know how well you would be able to do it, so he wanted your product at an "introductory trial reduced price". At the same time, you were happy to get the job, so you were willing to work for smaller pay at the beginning. But now that he's become satisfied with your work and your attitude, and you've learned to do the job better than before ... NOW your product should be worth more than before, not less.
Increase your hours ? ! ? Thanks a bunch, boss ! Work is not a product that sells at a quantity discount.