Answer: The required equation of the line is
![y=2x-6.](https://img.qammunity.org/2020/formulas/mathematics/middle-school/mar4tku37f6fmpqhag71cb3lbay5ybzj0o.png)
Step-by-step explanation: We are give to write the equation of a straight line with x-intercept 3 and passing through the point (5, 4).
Since the given line has x-intercept 3, so it will pass through the point (3, 0).
The slope of a line passing through the points (a, b) and (c, d) is given by
![m=(d-b)/(c-a).](https://img.qammunity.org/2020/formulas/mathematics/middle-school/l994x5mgafn1iyxedhlpex60fr6oq9126v.png)
Since the given line passes through the points (3, 0) and (5, 4), so its slope will be
![m=(4-0)/(5-3)=(4)/(2)=2.](https://img.qammunity.org/2020/formulas/mathematics/middle-school/g186nigv89y7t3t29lozky5l3ag2dler3g.png)
Therefore, the equation of the line is given by
![y-0=m(x-3)\\\\\Rightarrow y=2(x-3)\\\\\Rightarrow y=2x-6.](https://img.qammunity.org/2020/formulas/mathematics/middle-school/30tmiafo81z1rvi8mfmxbzxzn0ejz24lhs.png)
Thus, the required equation of the line is
![y=2x-6.](https://img.qammunity.org/2020/formulas/mathematics/middle-school/mar4tku37f6fmpqhag71cb3lbay5ybzj0o.png)