How to put 63 over 84 in simplest form

Mr. rose asked his students to draw a quadrilateral with 4 unequal sides. draw an example of this kind of quadrilateral.

The value, v, of kalani’s stock investments over a time period, x, can be determined using the equation v=750(0.80)^-x. what is the rate of increase or decrease associated with this account? 20% decrease 20% increase 25% decrease 25% increase

Can anyone explain to me how to do this? anything will .