we have that
The volume of a rectangular prism is given by the formula
where
V=252 cm3
H=3 cm
W=x cm
L=W+5 --------> L=x+5
substitute given values in the formula
Solve the quadratic equation
using the formula
a=3
b=15
c=-252
substitute
The values of x are
x=7 cm and x=-12 cm ( is not a solution because is a negative number)
The width is 7 cm
therefore
Is not possible for the width to be 7.5 cm