Asap asap asap 'm not sure if i put the box right

Add the two expressions 3.8b - 7 and 2.9b + 9 enter your answer in simplified form

Solve this system of equations. 12x − 18y = 27 4x − 6y = 10

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?