Find x+y, if12x+13y=29and 13x+12y=21

If given an equation of a line such as -1/2x+6 how would you create an equation of a line parallel and perpendicula to this line that goes through another point such as (4,10)

What is best way to getting answer for my exam is

Parks is wearing several rubber bracelets one third of the bracelets are tie-dye 1/6 are blue and 1/3 of the remainder are camouflage if parks wears 2 camouflage bracelets how many bracelets does he have on