Three Different Letters Are To Be Mailed To 3 Persons. If The Three Letters Are To Be Put At Random Into Three Envelopes

Solve the given system of equations. 2y= -x+9 , 3x-6= -15

Need on this geometry question. explain how you did it.

Is the product of two rational numbers irrational or rational? first, make a hypothesis by multiplying two rational numbers. then, use variables such as x=a/b and y=c/d and the closure property of integers to prove your hypothesis.