in simple interest, I=PRT
I=interest
P=principal
R=rate in decimal form
T=time in years usually, but could be months or weeks, dunno
I'm assuming that the 8.75 is 8.75% or 0.0875 in decimal
so
I=PRT
we know I, P, and R, so solve for T
I=PRT, divide both sides by PR
I/(PR)=T
subsitute
I=5425.00, P=15000, R=0.0875
I/(PR)=5425.00/(15000*0.0857)=4.133333333=T
so the time is 4.13333333 units of time