Part A.
We know there are 12 months in a year, then we have the following rule of three:
![\begin{gathered} 1\text{ year ------- 12 months} \\ x\text{ ---------- 72 months} \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/6og790yz7pggs57nrbtfob53jca0ig9649.png)
weere x denotes the corresponding years for 72 months and is given by
![x=\frac{(1\text{ year)(72 months)}}{\text{12 months}}](https://img.qammunity.org/2023/formulas/mathematics/college/fhx5uedyv9t5egyholnjbo1rhv7coqc97z.png)
that is,
![\begin{gathered} x=(72)/(12)\text{years} \\ x=6\text{ years} \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/hew0t6t4d7uo54wuv10zucyaaujksme9il.png)
Therefore, 72 months is equal to 6 years.
Part B.
In this case, we know there are 365 days in 1 year then our rule of three is
![\begin{gathered} 365\text{ days ------ 1 year} \\ x\text{ ----------- 6 years} \\ so,\text{ we get} \\ x=\frac{(365\text{ days)( 6 years)}}{\text{1 year}} \\ x=365*6\text{ days} \\ x=2190\text{ days} \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/k9nlo8i5g53py10posvrot1ymdpzvtpmbr.png)
this means that in 72 months (6 years) there are 2190 days.
Part C.
We know there are 24 hours in 1 day, so our rule of three is
![\begin{gathered} 24\text{ hours ------ 1 day} \\ x\text{ ---------- 2190 days} \\ \text{then, x is given as} \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/xpkcwniszfjwux9msqb82k02nko0usg1i3.png)
![\begin{gathered} x=\frac{(24\text{ hours)(2190 days)}}{\text{1 day}} \\ x=\text{ 24}*2190\text{ hours} \\ x=52560\text{ hours} \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/8tsct2c4jdohgt380pmh8ti939tsazzf7d.png)
Hence, 72 months are equal to 52560 hours