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3 years ago

7

R is a three digit number determine the digits of r from the clues the first digit is the answer when the third digit is divided

by 5 The second and third digits add to 8 The difference between the first and second digit is 2

1 answer:

madreJ [45]3 years ago

3 0

Answer:

135

Step-by-step explanation:

I believe this is the answer

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HELP SOMEONE ASAP LOTS OF POINTS

PSYCHO15rus [73]

Answer:

3 3/8

Step-by-step explanation:

4 5 27

--- - ----- = ------- or 3 3/8

1 8 8

7 0

3 years ago

A 75-gallon tank is filled with brine (water nearly saturated with salt; used as a preservative) holding 11 pounds of salt in so

Debora [2.8K]

Let $A(t)$ = amount of salt (in pounds) in the tank at time $t$ (in minutes). Then $A(0) = 11$ .

Salt flows in at a rate

$\left(0.6\dfrac{\rm lb}{\rm gal}\right) \left(3\dfrac{\rm gal}{\rm min}\right) = \dfrac95 \dfrac{\rm lb}{\rm min}$

and flows out at a rate

$\left(\dfrac{A(t)\,\rm lb}{75\,\rm gal + \left(3\frac{\rm gal}{\rm min} - 3.25\frac{\rm gal}{\rm min}\right)t}\right) \left(3.25\dfrac{\rm gal}{\rm min}\right) = \dfrac{13A(t)}{300-t} \dfrac{\rm lb}{\rm min}$

where 4 quarts = 1 gallon so 13 quarts = 3.25 gallon.

Then the net rate of salt flow is given by the differential equation

$\dfrac{dA}{dt} = \dfrac95 - \dfrac{13A}{300-t}$

which I'll solve with the integrating factor method.

$\dfrac{dA}{dt} + \dfrac{13}{300-t} A = \dfrac95$

$-\dfrac1{(300-t)^{13}} \dfrac{dA}{dt} - \dfrac{13}{(300-t)^{14}} A = -\dfrac9{5(300-t)^{13}}$

$\dfrac d{dt} \left(-\dfrac1{(300-t)^{13}} A\right) = -\dfrac9{5(300-t)^{13}}$

Integrate both sides. By the fundamental theorem of calculus,

$\displaystyle -\dfrac1{(300-t)^{13}} A = -\dfrac1{(300-t)^{13}} A\bigg|_{t=0} - \frac95 \int_0^t \frac{du}{(300-u)^{13}}$

$\displaystyle -\dfrac1{(300-t)^{13}} A = -\dfrac{11}{300^{13}} - \frac95 \times \dfrac1{12} \left(\frac1{(300-t)^{12}} - \frac1{300^{12}}\right)$

$\displaystyle -\dfrac1{(300-t)^{13}} A = \dfrac{34}{300^{13}} - \frac3{20}\frac1{(300-t)^{12}}$

$\displaystyle A = \frac3{20} (300-t) - \dfrac{34}{300^{13}}(300-t)^{13}$

$\displaystyle A = 45 \left(1 - \frac t{300}\right) - 34 \left(1 - \frac t{300}\right)^{13}$

After 1 hour = 60 minutes, the tank will contain

$A(60) = 45 \left(1 - \dfrac {60}{300}\right) - 34 \left(1 - \dfrac {60}{300}\right)^{13} = 45\left(\dfrac45\right) - 34 \left(\dfrac45\right)^{13} \approx 34.131$

pounds of salt.

7 0

2 years ago

Please help me with 10-12 +BONUS

dedylja [7]

Hi!

10.

This question is basically asking you, 10 is 40% of what number?

10 × 100 / 40 = 25

Fred must do 25 math problems.

12.

Bed & Bath = 40%

Clothing = 0.625 = 62.5%

Appliances = 20%

Electronics = 0.25 = 25%

Least to Greatest: Appliances (20%), Electronics (25%), Bed & Bath (40%), Clothing (62.5%).

4 0

3 years ago

adam drove 280 miles in 4 hours . on average, how fast did he drive in hours per mile ? Express your answer in simplest form

Ivan

Answer:

Step-by-step explanation:

$\frac{4 hours}{280 miles}$

$\frac{1 hour}{70 miles}$

5 0

4 years ago

If 9 were subtracted from three times a number, the result would be the same as if 4 were added to twice the number. what is the

amid [387]

3x-9=2x+4
3x-9+9=2x+4+9
3x=2x+13
3x-2x=2x-2x+13
x=13
Check:
3(13)-9=2(13)+4
39-9=26+4
30=30

4 0

3 years ago