Answer:
x+3
Step-by-step explanation:
If you factor 5 out of the denominator of the first expression, 5x+15 turns into 5(x+3).
Then, since you have x+3 in the numerator and denominator, it will cancel out.
The steps are shown below:
[tex]\frac{7x}{5x+15} *\frac{x+3}{8} \\\\=\frac{7x}{5(x+3)} *\frac{x+3}{8} \\\\=\frac{7x}{5} *\frac{1}{8} \\\\=\frac{7x}{40}\\[/tex]
Ive attached an image that shows an example of simplifying an expression using a the same technique.