Can some find the the answer than explain it Thank you

Is the number 128.439 a rational number

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

Which fraction represents the ratio 35 : 42 in simplest form