Answer:

Step-by-step explanation:
we know that
A relationship between two variables, x, and y, represent a proportional variation if it can be expressed in the form
or
Let
x -----> the amount of weight
y ----- the amount a spring will stretch
we know that
For x=80 lb, y=2.1 in
<em>Find the value of k (constant of proportionality)</em>

substitute the values

The linear equation is

How far will it stretch when 40 pounds is attached?
For x=40 lb
substitute the value of x in the linear equation and solve for y

if you have a zero exponent, the number (or the base) equals 1
make a proportion
<span>Let x = the amount of feet descended in 3 minutes (thus the total change of altitude of the balloon)
</span><span> 320 (feet per minute) / 1 (minute) = x (feet per minute) / 3 (minutes)
</span><span> 1) Divide: 320/1 = 320.
</span><span> 2) Multiply: 320 x 3= 960.
</span><span> The balloon that descends at a rate of 320 feet/minute (so, every minute, it descends 320 feet) descends a total of 960 feet in 3 minutes.
</span><span> The balloon's total change in altitude is -960 feet. </span>
Answer:
28
Step-by-step explanation:
let x be the number,
(3/4)x+5=26
(3/4)x=21
x=21*(4/3)
x=28