x = number of 1-cent stamps
y = number of 8-cent stamps
z = number of 12-cent stamps
We have 31 stamps all together, so x+y+z = 31.
"I have 4 more 1-cent stamps than 8-cent stamps" means we have the equation x = y+8. Whatever y is, add 8 to it to get x. Solve for y to get y = x-8.
You also have "twice as many one cent stamps as 12 cent stamps", so x = 2z. Solving for z gets you z = 0.5x
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x+y+z = 31
x+x-8+z = 31 ... y replaced with x-8
x+x-8+0.5x = 31 ... plug in z = 0.5x
2.5x-8 = 31
2.5x = 31+8
2.5x = 39
x = 39/2.5
x = 15.6
Your teacher made a typo somewhere because we should get a positive whole number result for x (since x is a count of how many 1-cent stamps we have).
The answer depends on the way you solved it.
I am assuming you take the base on which you perceived to be: . 5 and height which is 2.
So you must've ended with 1
But in actuality, you need to use the equation above and plug in 1.5 and 1
Subtract them and you should get 1.25
Do the same to the other side, you should get 6.
.125 x 6 = .875
Answer:
X=75
Y=110
Step-by-step explanation:
A straight line is 180, so add the equations that make a line and set them equal to 180
x+20+x+10=180
Combine like terms
2x+30=180
Subtract 30 from both sides
2x=150
Divide by 2
X=75
Same for y
y+y-40=180
2y-40=180
Add 40 to both sides
2y=220
Divide by 2
Y=110
Answer: D) 101
Step-by-step explanation:
By linearity, we can break it up into 2 integrals. The integral and derivative of f easily cancel out

I used the table for values of f(x) at 10 and -1. Wouldn't be surprised if this was part of a series of questions about f because I really can't see how you could use the hypothesis that f is twice differentiable on R. Same for the other table values. I'm curious about how you found the answer. Was it a different way?
Answer: 9 students
Step-by-step explanation:
15+8+3=26
35-26= 9