Joseph had to type an article containing 10,000 words. how many minutes did it take him? (1) joseph and kelly together can type a 75,000-word article in an hour and a half. (2) joseph types twice as fast as kelly does.

  0.3 hour or 18 minutes

Step-by-step explanation:

Kelly types half as fast as Joseph, so in the time it takes Joseph to type 10,000 words, Kelly can type 5000. That means they can type 15,000 words working together for that time. We are given their "working together" typing speed, so we can write the proportion ...

  (time for 15000 words)/(15000 words) = 1.5 hours/(75000 words)

Multiplying by 15000 gives ...

  (time for 15000 words) = (1.5 hours)×(15000/75000) = 1.5/5 hours

  time for 15000 words = 0.3 hours = 18 minutes

Joseph can type a 10,000 word article in 0.3 hours, or 18 minutes.

step-by-step explanation:

you can add the two numbers and divide the result by 2. or you can find the gap between the two numbers and add half of this to the smaller number.