The rate of interest of the instalment is 13%
The part payment of a loan is called Instalment
It is given that
The Cash price is $540
Instalment of $42
Time = 15 month = 15/12 = 1.25 years
Total Amount paid = 42 * 15 =$630
Interest Paid is $90
90 = 540 * 1.25 *Rate
Rate = 13%
The rate of interest of the instalment is 13%
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