filtering variable product with promo

How to explain this, lets try

I have a woocommerce webshop setup with variable products by weight.

For example one product looks like this

Product x
Variations:
25 grams 10 euro
50 grams 9,50
100 grams 18 euro
200 grams 35 euro

Now i want to make a promo sale from the 200 gram variation, for example i want to sell it for 30 euro instead of 35 euro, the other variations remain the same, so no promo

I want to show on the homepage my promo variation so the 200 gram product x for 30 euro using the sale products shortcode which filters out and shows the products with discount.
The problem is that it does not show the specific promo part in the variable product but it shows the whole variation as a kind of promo with “a from 10 euro” in front of it. But i obviously want it to show the detailed promo such as 200 grams from 35 euro (with strikethrough) for 30 euro.

Could that be achieved?

How can i acchieve this in woocommerce?

http://ww.wp.xz.cn/plugins/woocommerce/