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Sophie [7]
3 years ago
14

four pencils and a ruler cost $1. six pencils and three rulers cost $2.10. find the cost of three pencils and thirteen rulers.​

Mathematics
1 answer:
deff fn [24]3 years ago
5 0

Answer:

$ 5.65

Step-by-step explanation:

let the cost of a pencil and a ruler be $p and $r respectively.

4p +r= 1 -----(1)

6p +3r= 2.10

divide by 3 throughout:

2p +r= 0.70 -----(2)

Q: 3p +13r= ?

(1) -(2):

(4p +r) -(2p +r)= 1 -0.70

4p +r -2p -r= 0.30 <em>(</em><em>expand</em><em>)</em>

2p= 0.30 <em>(</em><em>simplify</em><em>)</em>

p= 0.30 ÷2 <em>(</em><em>÷</em><em>2</em><em> </em><em>on</em><em> </em><em>both</em><em> </em><em>sides</em><em>)</em>

p= 0.15

subst. into (1):

4(0.15) +r= 1

r +0.60= 1

r= 1 -0.60

r= 0.40

cost of three pencils and thirteen rulers

= 3p + 13r

= 3(0.15) + 13(0.40)

= 0.45 + 5.20

= $5.65

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Answer:

144

Step-by-step explanation:

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elixir [45]

well the formula to reflecting across the x-axis is (x,-y).so the final points are A'(2,-2)   B'(3,-7)  C(5,-5) ANSWER



additional information

By the way the -y in the formula does not mean every number will always be negative it means switch the sign  so if the point is (5,-7) than reflecting across the x-axis it would be (5,7)

5 0
3 years ago
An aquarium is leaking water at the rate of three quarts in 4 days.How many quarts are leaked in 1 week?How many days does it ta
Simora [160]

Answer:

\frac{21}{4} quarts

12 days

Step-by-step explanation:

Given that:

Amount of water leaked in 4 days = 3 quarts

To find:

Number of quarts leaked in 1 week?

Number of days taken for the leakage of 9 quarts of water?

Solution:

We can simply use unitary method or the ratio to find the answers of the questions asked in the statement.

As per question statement:

Amount of water leaked in 4 days = 3 quarts

Dividing by 4 on both sides:

Amount of water leaked in 1 day = \frac{3}{4} quarts

Multiplying by 7 on both sides:

Amount of water leaked in 7 days = \frac{3}{4}\times 7 = \frac{21}{4} quarts

Number of days taken for the leakage of 3 quarts = 4 days

Multiplying by 3 on both sides:

Number of days taken for the leakage of 3 \times 3 = 9 quarts = 4 \times 3 = <em>12 days</em>

6 0
3 years ago
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Galina-37 [17]

Answer:

D).  -5(x + 2)^2 - 2.

Step-by-step explanation:

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Stretch by factor 5 gives:

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makkiz [27]

Step-by-step explanation:

(4s + 2) × (5s² + 10s +3)

we know immediately the first and the last term of the result, because there is only one operation to build them :

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so, the first answer option is already eliminated.

let's multiply

4s×5s² + 4s×10s + 4×3s + 10s² + 20s + 6

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20s³ + 50s² + 32s + 6

so, the last answer option is correct.

4 0
2 years ago
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