Okay, so the rate is 1 job / hours, so:
1/3 + 1/7 (This covers both their work rates) = 1/n (n represents the time it take for them to work together)
Get the LCD:
7/21+ 3/21 = 1/n
10/21 = 1/n
Cross multiply:
10n = 21
n = 2.1
It will take them 2.1 hours, or 2 hours and 6 minutes
<span>A grain of sand has a diameter of slightly over 1 mm and the average diameter of a human cell is 8 micrometers. Putting them into common terms (meters) gives: 1.03 * 10^-3 m and 8*10^-6 m, respectively. Dividing the two to give a ratio leads to a value of (1.03*10^-3)/(8*10^-6), or 128.75 times longer for the grain of sand.</span>
Answer:
I think it's D
Step-by-step explanation:
I think 140 is the answer
Answer:
hey i can help if you want it
Step-by-step explanation: