To solve this (assuming that you mean simple interest) you need to first know the formula for exponential growth witch is S(1+(-)I) so with all of are numbers inputed it looks something like this 800(1+.0425) because, S=starting amount, I=interest rate, and T=Time (amount of time that goes by) back to the equation it would equal 1027 (rounded to the nearest dollar)
The answer to this question is that there are many integers with deifferent signs when added the answer is 8. For example, +13 and -5 are two integers with different signs when added the answer will b 8. The sum of integers +12 and -4 is also 8. +11 and -3, +10 and -2, +14 and -6 also gives 8 answer when added. There are many others.
To multiply fractions, you just multiply the top number by the top number and the bottom number by the bottom number. Also, you have to watch the sign.
In this case, we have a positive fraction multiplied by a negative fraction, meaning that our answer must be negative.
So we have- 2x7 / 4x9.
This is simplified to be- 14/36, or 7/18.
However, the answer is actually -7/18, since the number must be negative.