Okay, so i need to understand how to do these problems:

The spread of a flu virus is modeled by y= 1000/1+990e^(-.7t)
y is the total number infected after t days. In how many days will 350 people be infected with the virus?

log5(n) + log5(n+4)= 1


7^3x = 5^(x+2)


Evaluate logb(14/3b) if log b 2=0.2789, log b 3=0.4421, log b 7=0.7831


log3 + log(x+1)=1 solve for x