Write a system of equations:
x + y = 125
20x + 15y = 2100
Solving:
x = 125 - y
20(125 - y) + 15y = 2100
2500 - 20y + 15y = 2100
2500 - 5y = 2100
-5y = 2100 - 2500
-5y = -400
y=80
x + 80 = 125
x = 125 - 80
x = 45
The first charges 45$ per hour and the second charges 80$ per hour
a.
b.
The metal obey this law for values of strain until 0.05, where we have a linear relationship (each increase of 0.01 in the strain causes an increase of 100 in the stress). After this point, we don't have a linear relationship anymore.
c. Since an increase of 0.01 in the strain causes an increase of 100 in the stress, the slope is:

Now, calculating the coefficient b (y-intercept), we have:

So the equation is:

d.
The maximum value of stress is 560, and occurs at strain = 0.07.
Answer:
(a)
(b) 
Step-by-step explanation:
It is given that
.
(a)
(b)
![[\because \sin x=\dfrac{1}{\csc x}]](https://tex.z-dn.net/?f=%5B%5Cbecause%20%5Csin%20x%3D%5Cdfrac%7B1%7D%7B%5Ccsc%20x%7D%5D)

Therefore,
.
Answer:
B
Step-by-step explanation:
Subtract 150 from both sides
-5r ≥ -62.5
Divide both sides by -5
r ≤ 12.5
(The greater than sign flips around when you divide or multiply both sides by a negative number)