Answer:
z=-3 so 2y+3(-3)=-8, 2y-9=-8, add 9 to both sides 2y=1 divide both sides by 2, y=1/2, so 3x+4(1/2)+-3=-2, 3x+2-3=-2, 3x-1=-2, add 1 to both sides, 3x=-1, divide both sides by 3, x=-1/3
To find the IQR you first need to write it in numerical order
77, 81, 83, 84, 86, 86, 88, 92
IQR is just Q3 - Q1
Q1 is the middle of the first have, since it has an even set of 4 numbers in the first half you need to take the average of the two middle ones.. which is 82
Q3 done the same process would be 87.
87 - 82 = 5
IQR = 5