Just subtract them like normal number.
Example: π/2 - π/4
Just handle it like normal number:
π/2 - π/4 = 2π/4 - π/4 = (2π - π )/ 4 = π/4
Hope this helps.
If he earns 6% interest per year, then he will have had money in his investment account for three years.
I hope this answer helped you! If you have any further questions or concerns, feel free to ask! :)
ANSWER

EXPLANATION
The given equation is

Divide both sides by


Cancel out common factors on the left hand side,

For this solution to be a whole number, then

should be a factor of

.
The reason is that, factors of 6 will divide exactly in to 6 without a remainder, making the answer a whole number.
The whole numbers that are factors of 6 are,

Note that, the set of whole numbers are,
{

}