Yes, you can say that! Or you can say “letter that contains advice” or “letter that provides advice.”
A dangling modifier is a type of a modifier which is placed incorrectly or the noun it is supposed to modify isn't clearly stated in the sentence.
Having this in mind, the sentence which contains a dangling modifier is <span>A. Playing with the children, it was obvious they had a good time.
It should be rewritten somehow to say: It was obvious they had a good time playing with the children. </span>
A poem is your answer. Please comment if you want more examples :)
It takes 100 cents to make a $1 so 200 cents is $2 and 48 cents are left so in total it will be $2.48