I = prt calculates the amount of simple interest. I represents the interest, p the principle, r and the percentage rate and t the amount of time. We know that t = 6 years, p = 7000, and I = 1890.
So 1890 = 7000r6 1890 = 42000r
Divide both sides by 42000 1890 / 42000 = 42000r / 42000 r = 0.045.