36:21 in simplest form is 12:7, because 3 goes into both 36 and 21. Simplifying ratios is essentially the same thing as simplifying fractions. Once we have 12:7, we can't reduce any further, because 7 is prime.
Hope this helps!
Answer:
principle= 6000
time =9 years
rate = 7%
so,
compound interest = p((1+r/100)^t. -1)
= 6000((1+0.07)^9 -1)
=6000(1.84-1)
=6000*0.84
=5040