This is the place to post questions and discussions on usage and style. The members of the Wordwizard Clubhouse will also often be able to help you to formulate that difficult letter.
Can one say
a. My English and his are equally bad.
b. Our English is equally bad.
I am not sure quite why but it sounds slightly awkward although there is nothing actually wrong with it. I might use: "Our English is as bad as each other's".
I'm puzzled therefore I think.