<prompt> Translate the following text to EnglishAlipoogopa kwamba nguvu zake zingekuwa zikipungua alipokaribia miaka 30, Nash aliamua kwamba angetatua tatizo muhimu zaidi lisilotatuliwa katika dhana ya Riemann-Zeta.  <response>: Fearing his powers might be waning as he approached 30, Nash decided he would solve the most important unresolved problem in the Riemann Zeta conjecture. 