I'm going to assume the rate, 3.9%, is for one year.
7550 * 3.9 * 6 = $176, 670 is the simple interest earned in 6 years with a rate of 3.9% per year.
Since you have the formula, why don't you do it yourself?
130 (I have to write 20 character or more so I'm writing this)
For <span>12/15=47/50, we multiply 12/15 by (1/3)/(1/3) to get 4/5. For 47/50, we multiply it by (1/10)/(1/10) to get the same denominator and 4/7/5. They are not equal.
For 16/36 and 12/27, we'll notice that 36 and 27 are both multiples of 9, so we need to get that as the denominator! Multiply 16/36 by (1/4)/(1/4) because 9 goes into 36 4 times and 12/27 by (1/3)/(1/3) due to that 27 goes into 9 3 times, we get 4/9=4/9 - these are equal!
I challenge you to get the rest of them on your own using my techniques!</span>
there are 6 terms in the simplified expression