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<h2>Answer</h2>
Or as ordered pairs:
Lets solve our system of equations step by step
equation (1)
equation (2)
1. Solve for in equation (2)
equation (3)
2. Replace equation (3) in equation (1) and solve for
or
3. Replace the values of in equation (3) and solve for
- For
or
- For
or
So, the solutions of our system of equation are:
Answer: 44 hours.
Step-by-step explanation:
Marisol is being paid $792.
We know that the job took her 8 hours more than she expected, so if we define T as the time she expected, this job took her:
T + 8 hours.
The amount of money per hour that she expected is calculated as:
$792/T = X
And for those 8 extra hours, she won $4 less per hour, then we have:
$792/(T + 8hs) = X - $4
Then we have a system of equations:
$792/T = X
$792/(T + 8hs) = X - $4
To solve this, we can notice that in the first equation X is isolated, then we could replace that in the second equation to get:
$792/(T + 8hs) = $792/T - $4
Now we can solve this for T.
$792 = ($792/T - $4)*(T + 8hs) = $792 + $792*(8hs/T) - $4*T + $32*hs
0 = $792*(8hs/T) - $4*T + $32*hs
Let´s multiply this both sides by T
0*T = ($792*(8hs/T) - $4*T + $32*hs)*T
0 = $792*8hs - $4*T^2 +$32*T*hs
This is a quadratic equation, where i will write this witout units so it is easier to read and follow:
0 = -4*T^2 + 32*T + 792*8
The solutions cab be found by using the Bhaskara´s formula, these are:
Then the solutions are:
T = (-32 + 320)/-8 = -36 hours (This is a negative time, and it does not really have a meaning in this problem, so we can discard this option)
The other solution is:
T = (-32 - 320)/-8 = 44 hours.
Then we can conclude that she expected the job would take 44 hours in total.