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il63 [147K]
3 years ago
11

4x - 7y = 3 x - 7y = 15

Mathematics
1 answer:
charle [14.2K]3 years ago
5 0
\left \{ {{4x-7y=3} \atop {x-7y=15}} \right. \\\\
 \left \{ {{4x-7y=3} \atop {x=15+7y}} \right. \\\\ substitution\ method\\\\
4*(15+7y)-7y=3\\\\
60+28y-7y=3\\\\
60+21y=3\ \ \ \ | subtract\ \\\\
21y=-57\\\\
y=-\frac{57}{21}=-\frac{19}{7}\\\\
x=15+7*(-\frac{19}{7})=15-19=-4\\\\\ Solution :\  \left \{ {{y=-\frac{19}{7}} \atop {x=-4}} \right.
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Ron walks 0.5 mile on a track in 10 minutes. Stevie walks 0.25 mile on the track in 6 minutes find the unit rate for each walker
Firlakuza [10]

Answer:

Ron's speed = 3 miles/hour

Stevie's speed = 2.5 miles/hour

On comparing we see Ron is walking faster than Stevie.

Step-by-step explanation:

Given:

Ron takes 10 minutes to walk on a track to cover a distance of 0.5 miles

Stevie takes 6 minutes to walk on a track to cover a distance of 0.25 miles

To find their unit rates in mile per hour and choose the faster one.

Solution:

Unit rate in miles per hour signifies their speeds. Thus, we will find out their speeds.

Ron:

Distance= 0.5 miles

Time = 10 minutes = 10\ min\times \frac{1\ hr}{60\ min}=\frac{1}{6} hours

Speed = \frac{Distance}{Time}=\frac{0.5}{\frac{1}{6}}=0.5\times6=3\ miles/hour

Stevie

Distance = 0.25 miles

Time = 6 minutes = 6\ min\times \frac{1\ hr}{60\ min}=\frac{1}{10} hours

Speed = \frac{Distance}{Time}=\frac{0.25}{\frac{1}{10}}=0.25\times10=2.5\ miles/hour

Thus, we have

Ron's speed = 3 miles/hour

Stevie's speed = 2.5 miles/hour

On comparing we see Ron is walking faster than Stevie.

4 0
3 years ago
A population grows with an annual growth rate of 16.5 % per year. (a) what is the monthly growth rate
Shtirlitz [24]
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3 years ago
Which one should I choose
shutvik [7]

Answer:

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Step-by-step explanation:

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8 0
3 years ago
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enot [183]
How many books has she read so far? She's been doing this for 7 months, so so far she's read:

7*3=21

how many does she still need to read?

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so she needs to read 9 more books. With 3 books a month, this means:

9/3=3

so she needs to read 9 more books, which will take her 3 months!
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3 years ago
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Svet_ta [14]

Answer:

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Step-by-step explanation:

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8 0
2 years ago
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