Explanation:
Let,
- x = Kevin's age
- y = Kevin's mother's age
Given that,
Kevin's age + Mother's age = 61
x + y = 61
required equation for a)
![\rule{150pt}{2pt}](https://img.qammunity.org/2023/formulas/mathematics/college/i5tj7bm6uy89hevmpnt9bal70t01kn6ndy.png)
Now, we have two equations.
y - 3x = 1 -------(1)
y + x = 61 --------(2)
On solving them (using the substitution method),
![\left. \begin{cases} { y-3x = 1 } \\ { y+x=61 } \end{cases} \right.](https://img.qammunity.org/2023/formulas/mathematics/college/5seict5ve05tpk7mbfa1778naqv7gvg6uv.png)
Take ----(1)
![y-3x=1 \\y=3x+1](https://img.qammunity.org/2023/formulas/mathematics/college/cqxysuxqi285soargpzdhd0niqr1kl388g.png)
Now, substitute the value of y in ----(2)
![y + x = 61\\3x+1+x=61 \\4x+1=61 \\4x=60 \\x = 15](https://img.qammunity.org/2023/formulas/mathematics/college/svb0oqnfy9ucfjbzqk7ruvmmf3ptg3z743.png)
Substitute the value of x in -----(1),
![y=3* 15+1 \\y= 45+1\\y = 46](https://img.qammunity.org/2023/formulas/mathematics/college/9mp6c3s5rdxmgvx4g8cmi6exk70dfy60sp.png)
So,
![\boxed{\bf\:x = 15, \:y = 46}](https://img.qammunity.org/2023/formulas/mathematics/college/1zv1es39hgftbnzb27unhazq6lb9mkqfn9.png)
Now, by graphing them (see the attachment), the point of intersection is O (15, 46). Hence, from this we can infer that, Kevin is 15 years old while his mother is 46 years old.
answer for b)
![\rule{150pt}{2pt}](https://img.qammunity.org/2023/formulas/mathematics/college/i5tj7bm6uy89hevmpnt9bal70t01kn6ndy.png)