Full explanation if you can.
1. the ratio of boots to sandals in a shoe store is 8: 3. if there are 245 more boots than sandals in the store, how many boots are there? ?

392 boots. If you divide everything into "sets" of an unknown amount, there are 5 more "sets" of boots than sandals, also known as the 245 boots. So if you divide 245 by 5, you'll get the number of items in a "set". Then just multiply by 8 from the 8:3 ratio. If you check it, it will come out to 392 boots to 147 sandals, which I think is ridiculous since sandals are supposed to come in pairs so  you should never have a odd number. But anyway, 392 - 147 = 245