Ola

C = 2000 - 500 = 1500

J = C*i*t

J = 500

C = 1500

t = 5

i = ?

500 = 1500*5*i

i = 500/7500 = 1/15 %

pronto

J = C.i.t/100

500 = 2000i.5/100

500 = 100i

500/100 = i

i = 5%