Help pleease waht is .50 as a fraction

Describe all the numbers that when rounded to the nearest thousand are 645,000

Identify the initial amount a and the growth factor b in the exponential function. a(x)=680*4.3^x

Tatiana wants to give friendship bracelets to her 32 classmates. she already has 5 bracelets, and she can buy more bracelets in packages of 4. write an inequality to determine the number of packages, p, tatiana could buy to have enough bracelets.