Answer:
x = 4 1/2 or 4.5 cm
Explanation:
We know the perimeter of the rectangle is given by the formula
P =2(l+w)
19 = 2(2.5 + (2.5+x))
Simplifying
19 = 2( 5+x)
Distribute
19 = 10 + 2x
Subtract 10 from each side
19-10 = 10-10 + 2x
9 = 2x
Divide each side by 2
9/2 = 2x/2
4.5 = x