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Alex Ar [27]
2 years ago
9

Adam is working two summer jobs, making $9 per hour washing cars and $8 per hour walking dogs. Last week Adam earned a total of

$116 and worked 6 more hours walking dogs than hours washing cars. Determine the number of hours Adam worked washing cars last week and the number of hours he worked walking dogs last week.
Mathematics
1 answer:
Phantasy [73]2 years ago
8 0

Answer:

Washing cars= 4 hours

Walking dogs= 10 hours

Step-by-step explanation:

You want to start by creating equations. So one thing we know is that he makes $9 an hour washing cars(x) and $8 walking dogs(y).

$9x+$8y=$116

The second Equation is based off of the hours worked. We know that he worked 6 hours more walking the dogs than he did washing cars, so we can take x(being the washing hours) and add 6 to it to equal y (the number of dog hours).

y=x+6

Now You plug what y equals into the first equation to solve for x.

9x+8(x+6)=116     Next distribute the 8 to each term.

9x+8(x)+8(6)=116

9x+8x+48=116     Add the like terms together (9x+8x)

17x+48=116         Subtract the 48 from both sides

     -48  -48

17x=68             Now divide by 17 on both sides.

______

17    17

x=4                 Finally we can take x and plug it back in to one of the equations in order to solve for y. I'm going to choose the second equation.

y=(4)+6

y=10

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B) To solve this problem we will use formula for a growth of population:
final = initial * (1+percentage)^{t}
Where:
final = final number of students
initial = initial number of students
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We can insert numbers and solve for t:
240= 120* (1+0.12)^{t}  \\ 2=1.12^{t}   \\ log2=log(1.12^{t} ) \\ log2=t*log1.12 \\ t= \frac{log2}{log1.12}  \\ t=6.12years

For Plan B we can use simple formula
increase = 120
increase per year = 20
number of years = increase / (increase per year) = 120 / 20 = 6 years

Plan B is better to double the <span>enrollment.


C)We use same steps as in B) to solve this.
</span>

360= 120* (1+0.12)^{t} \\ 3=1.12^{t} \\ log3=log(1.12^{t} ) \\ log3=t*log1.12 \\ t= \frac{log3}{log1.12} \\ t=9.69years

For Plan B we can use simple formula
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increase per year = 20
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Plan A is better to triple the enrollment.
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