What is a 15% discount of 29.75

29.75/x=100/15
(29.75/x)*x=(100/15)*x       - we multiply both sides of the equation by x
29.75=6.66666666667*x       - we divide both sides of the equation by (6.66666666667) to get x
29.75/6.66666666667=x
4.4625=x
x=4.4625

now we have:
15% of 29.75=4.4625

It is rigid. it is isometric. the size is preserved.