Hi there The simple interest formula is I=prt I interest changes P amount of the loan 6000 R interest rate T time( number of months/12 months)
The interest in 36 months at a 10% I=6,000×0.1×(36÷12)=1,800 The interest in 48 months at a 12% 6,000×0.12×(48÷12)=2,880 she will save 2,880−1,800=1,080