Solve for L: d= (LR_2)/(R_2+R_1
d= (LR_2)/(R_2+R_1) d(R_2+R_1)= LR_2 d(R_2+R_1)/(R_2)= L L= d(R_2+R_1)/(R_2) The answer I obtained is the same answer as the third choice. L= d(R_2+R_1)/(R_2) L= (R_2+R_1)d/(R_2) L= (R_2+R_1)(d)/(R_2) L= ((R_2+R_1)(d))/(R_2)