Let l=length and w=width
From the question given;
w= l - 5
perimeter = 30
perimeter = 2l + 2w
2l + 2w = 30
2l + 2(l - 5) = 30
2l + 2l - 10 = 30
4l - 10 = 30
add 10 to both-side of the equation
4l = 30 + 10
4l = 40
divide both-side of the equation by 4
l = 10
substitute l=10 into
2l + 2w = 30
2(10) + 2w = 30
20 + 2w = 30
substract 20 from both-side of the equation
2w = 10
divide both-side of the equation
w = 5
Length of quilt = 10 inches
Width of quilt = 5 inches
The quilt dimensions are 10 inches by 5 inches