Which expression has a value greater than a 100

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?

What is the missing reason in the proof? segment addition congruent segments theorem transitive property of equality subtraction property of equality?

What is the solution to the system of equation graphed belowa.(0,-4)b.(2,5),1),-3)