Answer:
Ellen invested $60 and Bob invested $140
Step-by-step explanation:
let the two amounts invested by 3x and 7x
(notice 3x : 7x = 3 : 7 )
then 3x + 7x = 200
10x = 200
x = 20
then 3x = 3(20) = 60
and 7x = 7(20) = 140
60+140=200
Substitute 136.5 for y.
Compare this equation with 
a = 1, b = - 191, c = 8190
or
or
or
or
or
or
x = 126 or x = 65
Hence, the points on the curve are (65, 136.5) and (126, 136.5).
The width of the air space is the distance between these points.
Width = 
= 
= 126 - 65
= 61
Hence, width of the air space is 61m.
Y=mx+b
y=(1200-2x)/3
y=1200/3-2/3x
y=400-2/3x
y=-2/3x+400
Answer:
1)-9
2)16
3)-2
Step-by-step explanation:
1)
-3x + 4 = 31
-3x = 31 - 4
-3x = 27
-x = 27/3
-x = 9
x = -9
2)
2x + -10 = 22
2x = 22 + 10
2x = 32
x = 32/2
x = 16
3)
40 = 32 – 4r
-4r = 40 - 32
-4r = 8
-r = 8/4
-r = 2
r = -2
