This is a multi-step problem, and I am lost:
These are the previous steps:
dividethe value of xby 2. Her stuffing rate is
I do not understand what they are talking about:
We solve this equation for x. Multiply both sides by the LCD of the three fractions, 12x, and simplify.
Subtract 3100x from both sides.
Divide both sides of the equation by the coefficient of x.
1 Answer | Add Yours
For step `1` note that:
amount of work = rate * time
Therefore, rate = amount of work/time
Since Kevin can stuff `1,550` shrimp in `6` hours the amount of work is `1,550` and the time is `6` , hence his rate is `1550/6` .
For the step `2` , we will apply the same formula. This time we do not know the time it takes her sister to stuff `1,550` shrimp, so we let it as x. So, the rate of her sister is `1550/x` .
For step` 3` , since we know that they can stuff `1,550` shrimp in `4` hours together the combine rate is `1550/4` . We will apply addition since we are ''combining'' rates.
Take the sum of the rates of Kevin and her sister.
`1550/6 + 1550/x = 1550/4`
Identify the LCD.
The denominators are `6` , `x` , and` 4` . Since there is a variable `x ` we will include it on the LCD.
Take the lcm (least common multiple) of `6` and `4` .
The multiples of` 6 ` are: `6,12,18, 24, 30, 36, 42, 48, 54, 60` .
The multiples of `4` are:` 4, 8, 12, 16, 20, 24, 28, 32, 36, 40` .
Therefore, the LCM is `12` . Therefore the LCD is `12 * x = 12x` .
To get rid of the denominators we multiply both sides by the LCD.
`(12x)*(1550)/(6) + (12x)*(1550)/(x) = (12x)*(1550)/(4)`
Simplifying `12/6 = 2` ,` (12x)/(x) = 12 ` and `(12x)/(4) = 3` .
`(2x*1550) + (12*1550)=(3*1550)`
`3100x + 18600 = 4650x`
Since, we are solving for `x` we put the terms with` x` on one side. So, we need to move the` 3100x ` to the right side. Since `3100x ` is being added on left side, we use the opposite operation of addition which is subtraction. So, subtract` 3100x` on both sides.
`3100x + 18600 -3100x = 4650x - 3100x`
`18600 = 1550x`
Isolate the `x` on right side by dividing `1550` on both sides.
`(18600)/(1550) = (1550x)/(1550)`
`12 = x` or `x = 12`
Therefore, the time it takes for Kevin's sister to stuff `1550` shrimp is `12` hours.
Also, remember that the original question is to find the amount of time the sister takes to prepare 775 shrimp. You have found the time to do 1550 shrimp (12 hours), so the time to do 775 shrimp is 1/2 this or 6 hours. (Hence the hint in step 1 to find x and divide by 2.)
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