I hope this helps you
10.x-10.y
10 (x-y)
Answer:
first, we put them in order
78,[80],83,(85),86,[87],90
Q1 = 80
Q2 (median) = 85
Q3 = 87
Interquartile range (IQR) = Q3 - Q1 = 87 - 80 = 7 <==
Hope this helps!
X+y+z=22
(x+y+z+t)/4=8
subsitute
x+y+z=22
(22+t)/4=8
multiplly by 4
22+t=32
subtract 22
t=10
the fourth number is 10
Just to be different we'll start with intercept intercept form which says the line through x intercept (a,0) and y intercept (0,b) is

Through (4,0) and (0,-2) that's

Multiply through by the common denominator of 4 for standard form:
x - 2y = 4
For slope intercept form we solve for y
-2 y = -x + 4
y = (1/2) x - 2
We see our slope is (1/2) and we go through (4,0) so point slope form is
y - 0 = (1/2)(x - 4)
y = (1/2)(x-4)