Answer
$(2\cdot3+3)\cdot 5$
Work Step by Step
Note that $45=9 \cdot 5$.
The first three numbers from the left can be grouped together to give:
$(2 \cdot 3 + 3) \cdot 5 = (6+3)\cdot5 = 9\cdot 5 = 45$
Thus, the parentheses can be used to enclose the first three numbers to obtain:
$=(2\cdot3+3)\cdot 5$
