Answer:
Step-by-step explanation:
Using formula 
a= 650
b= 800
and c is the unkown
Answer:
r < 1/3
Step-by-step explanation:
21r<7
Divide each side by 21
21r/21<7/21
r < 1/3
Simple interest:
Simple interest is simple. Each year, the interest is calculated as a percentage of the principal, as follows: Interest= (principal) x (rate) x (time).
Compound interest:
Compound interest<span> is calculated on the principal amount and also on the accumulated </span>interest <span>of previous periods.</span>