Show me how to solve math word problems

Ab and bc form a right angle at point b. if a= (-3,-1) and b= (4,4) what is the equation of bc?

F(x) = 1/x g(x)=x-4 can you evaluate (g*f)(0) ? why or why not?

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