How to work out halfway between 1.1 and 1.2

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?

Ze trinomial x2 + bx – c has factors of (x + m)(x – n), where m, n, and b are positive. what is ze relationship between the values of m and n? explain how you got ze answer

One of the solutions to x2 - 2x – 15 = 0 is x = -3. what is the other solution? ox=-5 ox= -1 0 x=1 x = 5