NEED HELP PLS Use addition to solve the sytem if linear equation. Include all of your work in your final answer.
{-x -y = 4
{x + 2y = 4

Andrea went to the store to buy sweater that was on sale for 40% off the original price it was then put on clearance an additional 25% off the sale price she also use a coupon that saved her an additional five dollars and j did not spend more than $7.60 for the sweater what are the possible values for the original price of the sweater?

Ammonia molecules have three hydrogen atoms and one nitrogen atom.how many of each atom arein five molecules of ammonia

1- what do you think the product of a nonzero rational number and an irrational number is? is it rational or irrational? make use of variables, the closure property of integers, and possibly a proof by contradiction to prove your hypothesis.2- why do we have to specify that the rational number must be nonzero when we determine what the product of a nonzero rational number and an irrational number is? if the rational number were 0, would it give us the same result we found in the first question?