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2 years ago

Mary's age is 10 years less than 2 times Joe's age. If the difference between their ages is 30, how old is Mary?

Mathematics

2 answers:

svlad2 [7]2 years ago

7 0

Answer:

m=mary age

j=joe age

m=2j-10

m-j=30

rewrite

m=2j-10

m=j+30

so that means that

2j-10=j+30

-j

j-10=30

+10

j=40 so lets plug this in

m=2(40)-10

m=70

Hope This Helps!!!

zheka24 [161]2 years ago

4 0

Answer:

its 5

Step-by-step explanation:

cause 2 divided by 30is 15 minus 10 its 5

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Is how many student passed the math test a statistical question

Soloha48 [4]

Answer:

No it is not statistical

Step-by-step explanation:

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2 years ago

Alex wants to find out how many ducks there are in a park.

Fiesta28 [93]

An estimate for the number of ducks would be 62.

There were 30 the first day.
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Add 30 and 32 to get our estimate.

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2 years ago

"a u.S. 1-cent coin (a penny) has a diameter of 19 mm and a thickness of 1.5 mm". Assume the coin is made of pure copper, whose

choli [55]

the question is Calculate the value of the copper in the coin

Step 1

Find the volume of the coin

we know that

the volume of a cylinder is equal to

$V=\pi r^{2}h$

where

r is the radius of the coin

h is the thickness of the coin

in this problem we have

Diameter=19 mm=1.9 cm

r=D/2------> r=1.9/2=0.95 cm

h=1.5 mm=0.15 cm

substitute the values in the formula

$V=\pi*0.95^{2}*0.15=0.425\ cm^{3}$

Step 2

Find the mass of copper in the coin

we know that

the density is equal to

$Density=mass/volume$

Solve for the mass

$mass=Density*volume$

we have

$Density=8.9\ gr/cm^{3}\\Volume=0.425\ cm^{3}$

substitute in the formula

$mass=8.9*0.425=3.785\ gr$

Step 3

Find the cost

we know that

the market price of the copper is $2.15 per pound

1 pound=453.592 grams

convert gram to pounds

3.785 gr=3.785/453.592=0.0083 pounds

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the answer is

$0.02

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3 years ago

What is 15% of 140

Mariulka [41]

15% of 40

Of = Multiplication

15% Multiply by 40

Set up a equation

15/100= x/140

Cross Multiply

15* 140= 100*x

2100= 100x

Divide both sides by 100x

2100/100x= 100x/100x

X= 21

3 0

3 years ago

Read 2 more answers

*7. A family going on vacation rents a van for $160 plus $75 per day. The total bill was $760. How many days was the van rented?

Lina20 [59]

The answer is 7 days

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2 years ago