If the regular price of a tent is 13 and Harold has a coupon for 13 off, this means Harold has been subsidized by a factor of 13. The amount Harold will pay will be 13 less than t which is t-13 i.e 13 subtracted from the total regular price.
Don’t understand what your asking in the first one. Choosing a vowel out of the word counting would be 3/8. And picking a consonant out of the word prime would be 3/5.
