Hello,
For a website i need to make a price check form, but i can't really script, so can someone help me PLEASE!,

i need a imput for size: (height size in cm) x (width size in cm)

imput for quantity

+ 17,50 starting costs
+ 12,50 sending costs

=total in ,-

let's say if you put in height cm 10 and in widht 20 cm and quantity 50
0,01 x 0,02 = 0,02 m2
0,02 (square meters) x 50 (quantity) = 1 square meter

then multiply the square meter with;
if it is between 0 or 1 square meter it got to be multiplied 115,-
if it is between 1 or 2 square meter it got to be multiplied 105,-
if it is between 2 or 3 square meter it got to be multiplied 90,-
if it is between 3 or 4 square meter it got to be multiplied 85,-
if it is between 4 or 5 square meter it got to be multiplied 70,-

add 17,50 starting costs
add shipping 12,50 sending costs

And the total is = ,-

Please help me.
btw sorry for my bad english