Your answer will be \(x^{2} -2xy- 15y^{2}\)
To get this you have to multiply individually across the parenthesis. Like so:
x(x+3y)
↓
\(x^{2} +3xy\)
-5y(x+3y)
↓
\(-5xy-15y^{2}\)
Now we add these two expressions together: \(x^{2} +3xy\) + \(-5xy-15y^{2}\)
Next, we combine like terms: \(x^{2} -2xy- 15y^{2}\)
Since nothing else can be simplified, this is our answer. Hope this helped!!!
