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3 years ago

The sum of twice a number and 7 divided by 3 is 7 what is the number

Mathematics

2 answers:

dsp733 years ago

5 0

let "a number" = x

(x + 7)/3 = 7

Note the equal sign. What you do to one side, you do to the other. Do the opposite of PEMDAS.

First multiply 3 to both sides

(x + 7)/3(3) = 7(3)

x + 7 = 21

Next, subtract 7 from both sides

x + 7 (-7) = 21 (-7)

x = 14

14 is your number

hope this helps

marishachu [46]3 years ago

4 0

the answer is 7

n=7

2x7+7/3=7

14=7=21

21/3=7

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aniked [119]

Answer:

Step-by-step explanation:

Bottom triangle

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b = 4 + 4 = 8 cm

h = 5.75

Area = 1/2 * 5.75 * 8

Area = 23 cm^2

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3 years ago

Rachel ate 1 4/6 brownies, and brandy ate 6/7 of a brownie. how many brownies did they eat altogether?

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Answer:

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Step-by-step explanation:

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3 years ago

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tino4ka555 [31]

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Step-by-step explanation:

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3 years ago

Without actually writing the following explain how to expand (x+3)^7 using the binomial theorem

padilas [110]

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Step-by-step explanation:

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3 years ago

(1 point) A fish tank initially contains 15 liters of pure water. Brine of constant, but unknown, concentration of salt is flowi

Drupady [299]

Answer:

a. $\dfrac{dx}{dt} = 6\frac{2}{3} \cdot c$

b. $x(t) = 6\frac{2}{3} \cdot c \cdot t$

c. $c = \dfrac{3}{8} \ g/L$

Step-by-step explanation:

a. The volume of water initially in the fish tank = 15 liters

The volume of brine added per minute = 5 liters per minute

The rate at which the mixture is drained = 5 liters per minute

The amount of salt in the fish tank after t minutes = x

Where the volume of water with x grams of salt = 15 liters

dx = (5·c - 5·c/3)×dt = 20/3·c = $6\frac{2}{3} \cdot c \cdot dt$

$\dfrac{dx}{dt} = 6\frac{2}{3} \cdot c$

b. The amount of salt, x after t minutes is given by the relation

$\dfrac{dx}{dt} = 6\frac{2}{3} \cdot c$

$dx = 6\frac{2}{3} \cdot c \cdot dt$

$x(t) = \int\limits \, dx = \int\limits \left ( 6\frac{2}{3} \cdot c \right) \cdot dt$

$x(t) = 6\frac{2}{3} \cdot c \cdot t$

c. Given that in 10 minutes, the amount of salt in the tank = 25 grams, and the volume is 15 liters, we have;

$x(10) = 25 \ grams(15 \ in \ liters) = 6\frac{2}{3} \times c \times 10$

$6\frac{2}{3} \times c =\dfrac{25 \ grams }{10}$

$c =\dfrac{25 \ g/L }{10 \times 6\frac{2}{3} } = \dfrac{25 \ g/L}{10 \times \dfrac{20}{3} } =\dfrac{3}{200} \times 25 \ g/L= \dfrac{75}{200} \ g/L = \dfrac{3}{8} \ g/L$

$c = \dfrac{3}{8} \ g/L$

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3 years ago