Calculate sample size?

You are interested in studying the relationship between sodium consumption and the development of hypertension. 32% of Americans are hypertensive (systolic blood pressure>140), and a further 29% are prehypertensive (140≥SBP>120). Detecting a 1 mm Hg SBP elevation with 80% power at the 0.05% significance level will require 1709 study participants.

How many total people will you have to identify to have 1709 normotensives (SBP≤120mmhg) for your study? How many will you have to identify if you just exclude hypertensives?

I am not really sure on how to approach this question at all, I don't have the effective size or SD and I have no idea what to do with the percentages.

Thank you for your time and help! :)