) Jennifer and Krystal have to stuff and mail 1000 envelopes for a new marketing campaign. Jennifer can do the job alone in 6 hours. If Krystal helps, they can get the job done in 4 hours. How long would it take Krystal to do the job by herself?

12 hours

Step-by-step explanation:

Let's call the Jennifer's speed J, and the Krystal's speed K.

If Jennifer works alone, she can do the job in 6 hours, so:

J*6 = 1000

J = 1000/6 = 500/3

If Jennifer and Krystal work together, they can do the job in 4 hours, so:

(J+K)*4 = 1000

J+K = 250

Using the value of J, we can find K:

500/3 + K = 250

K = 250 - 500/3 = 250/3

Now, to find the time that Krystal would take if she works alone:

K * time = 1000

250/3 * time = 1000

time = 1000/ (250/3) = 1000*3/250 = 12 hours

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47 - 90 = 43

43 - 180 = x

x = 137