Let's solve this problem step by step:
So we know that Isaac sold 'x' number of tubs of dough
⇒ and that each tub of dough is worth 15 dollars
⇒ means he made '
dollars from selling 'x' tubs of dough
⇒ coincidently, we know that he made a total of $165
⇒ So the equation is:

Answer: 15x = 165
Hope that helps!