4a^2+8a-20=0
by completing the square

I'm not sure but I think it is a=−1±6√ 
a≈1.44948974,−3.44948974

Okay so looking at the problem, the conversion factors we are going to need are from days to hours and from minutes to hours. Let's start with the days to hours first. If there are 24 hours in a day and we have 58 days then 24x58 would get us the hours that we need. So we would get 1392 hours. Add that to the hours already present and you get 1407 hours and 30 minutes. Since 30 minutes is half of one hour you can either use a fraction or decimal to give your 1407.5 hours or  hours