A certain solution of salt water is 10% salt and weighs 50 pounds. more salt must be added to produce a solution that is 25% salt. if x represents the pounds of salt to be added, which of the following expressions represents the number of pounds of salt in the 25% solution?
a) 0.25 (x+50)
b) 0.25x
c) 1.25 (x+50)