Interest = (Principal * Rate * Time)/100
Make Time the subject of the formula
Cross multiply both sides
Interest * 100 = Principal * Rate * Time
100 I = PRT
Divide both sides by PR
100 I/PR = PRT/PR
100 I /PR = T or T = 100 I / PR
Input the values
T = (100 * 235.50)/ 7850 * 2
T = 23550/15700
T = 1.5 years - the unit of time in this topic is always in years except if stated otherwise
P - Principal R - Interest rate T - Time I - Interest