I can't get this. I've been stuck on this for at least an hour

If there is 20 dogs in the shelter and 5 dogs get homes, and then 43 more dogs come. how many dogs are there in the shelter?

How many 3-digit numbers can you write using only digits 1 and 7? (of course, digits can repeat.) how many 3-digit numbers can you write using only digits 1 and 7? (of course, digits can repeat.)

Ataxi company charges $3 for pick-up plus $0.65 for each mile. select the expressions that represent the cost in dollars for a taxi pick-up and m miles. mark all that apply.