find the change to find the interest change=186000-129000=57000
simple interest=time times rate times principal time is in years (8) rate is in decimal principal is amount invested (129000)
so interest is 57000 57000=(8)(r)(129000) 57000=1032000r divide both sides by 1032000 0.05523255813953488372093023255814=r or 5.523255813953488372093023255814% rounded 5.5%
