What point of concurrency is this and why?

What is the distance between (–2 1/2,-3) and (1, –3)?

Serena is making an experiment. for that, she needs 20 grams of a 52% solution of salt. she has two large bottles of salt water: one with 40% and the other with 70% of salt in them. how much of each must she use to make the solution she needs? i am in need of

Which expression is the factorization of x^2+10+21