I have put the formulae outside the cells in columns C and D , so that you can look at the logic and confirm that it is acceptable. I do not want revisions later on.
I'm not so sure what you're asking for is really what you want; all the rows in your sample data are within +/-20% of both support and resistance. In fact the difference between support and resistance in all cases is of the order of 5% or 6% and the FUTURE value is always between them.
I'm just wondering if you want the price to be within 20% of the difference between support and resistance, rather than just be within 20% of the support or resistance levels? (I'm just guessing that you want to trade when the price gets close to support or resistance… perhaps you want to try and trade oscillating instruments?)