Answer:
a. ![5 \frac{21}{40}](https://tex.z-dn.net/?f=5%20%5Cfrac%7B21%7D%7B40%7D%20)
b. ![\frac{1}{42}](https://tex.z-dn.net/?f=%20%5Cfrac%7B1%7D%7B42%7D%20)
Step-by-step explanation:
![a. \: 12 \frac{2}{5} - 6 \frac{7}{8}](https://tex.z-dn.net/?f=a.%20%5C%3A%2012%20%5Cfrac%7B2%7D%7B5%7D%20%20-%206%20%5Cfrac%7B7%7D%7B8%7D%20)
![\frac{62}{5} - \frac{55}{8}](https://tex.z-dn.net/?f=%20%5Cfrac%7B62%7D%7B5%7D%20%20-%20%20%5Cfrac%7B55%7D%7B8%7D%20)
![\frac{62}{8} \times \frac{8}{8} - \frac{55}{8} \times \frac{5}{5}](https://tex.z-dn.net/?f=%20%5Cfrac%7B62%7D%7B8%7D%20%20%5Ctimes%20%20%20%5Cfrac%7B8%7D%7B8%7D%20%20-%20%20%20%5Cfrac%7B55%7D%7B8%7D%20%20%20%5Ctimes%20%20%5Cfrac%7B5%7D%7B5%7D%20)
![\frac{62 \times 8 - 55 \times 5}{40}](https://tex.z-dn.net/?f=%20%5Cfrac%7B62%20%5Ctimes%208%20-%2055%20%5Ctimes%205%7D%7B40%7D%20)
![\frac{221}{40}](https://tex.z-dn.net/?f=%20%5Cfrac%7B221%7D%7B40%7D%20)
![5 \frac{21}{40}](https://tex.z-dn.net/?f=5%20%5Cfrac%7B21%7D%7B40%7D%20)
![b. \: \frac{3}{14} - \frac{4}{21}](https://tex.z-dn.net/?f=b.%20%5C%3A%20%20%5Cfrac%7B3%7D%7B14%7D%20%20-%20%20%5Cfrac%7B4%7D%7B21%7D%20)
![\frac{3}{14} \times \frac{3}{3} - \frac{4}{21} \times \frac{2}{2}](https://tex.z-dn.net/?f=%20%5Cfrac%7B3%7D%7B14%7D%20%20%5Ctimes%20%20%5Cfrac%7B3%7D%7B3%7D%20%20-%20%20%5Cfrac%7B4%7D%7B21%7D%20%20%5Ctimes%20%20%5Cfrac%7B2%7D%7B2%7D%20)
![\frac{3 \times 3}{42} - \frac{4 \times 2}{42}](https://tex.z-dn.net/?f=%20%5Cfrac%7B3%20%5Ctimes%203%7D%7B42%7D%20%20-%20%20%5Cfrac%7B4%20%5Ctimes%202%7D%7B42%7D%20%20)
![\frac{1}{42}](https://tex.z-dn.net/?f=%20%5Cfrac%7B1%7D%7B42%7D%20)
Hope it is helpful....
Your answer is 36 times 2
Answer: ![\frac{12}{7}\ \text{hours}](https://tex.z-dn.net/?f=%5Cfrac%7B12%7D%7B7%7D%5C%20%5Ctext%7Bhours%7D)
Step-by-step explanation:
Given
New mail carrier takes 4 hours for delivery i.e.
New mail carrier completes
part of work in 1 hour
Old mail carrier takes 3 hours for delivery i.e.
mail carrier completes
part of work in 1 hour
If they work together, they complete the work in x hours i.e.
![\Rightarrow \dfrac{1}{x}=\dfrac{1}{4}+\dfrac{1}{3}\\\Rightarrow \dfrac{1}{x}=\dfrac{3+4}{12}\\\Rightarrow x=\dfrac{12}{7}\ \text{hours}](https://tex.z-dn.net/?f=%5CRightarrow%20%5Cdfrac%7B1%7D%7Bx%7D%3D%5Cdfrac%7B1%7D%7B4%7D%2B%5Cdfrac%7B1%7D%7B3%7D%5C%5C%5CRightarrow%20%5Cdfrac%7B1%7D%7Bx%7D%3D%5Cdfrac%7B3%2B4%7D%7B12%7D%5C%5C%5CRightarrow%20x%3D%5Cdfrac%7B12%7D%7B7%7D%5C%20%5Ctext%7Bhours%7D)
The answer is about 113.1 feet squared