Answer:
3x² + 30x
Step-by-step explanation:
width of a box = x units.
height of a box = 3 units.
length of a box = (x + 10) units.
Volume of the box = length × width × height
= (x + 10) * x * 3
= (x + 10) * 3x
= 3x² + 30x
Volume of the box = 3x² + 30x
