Charles's Law Definition

Charles's Law is an ideal gas law where at constant pressure; the volume of an ideal gas is directly proportional to its absolute temperature.

where:
V_i = initial pressure
T_i = initial temperature
V_f = final pressure
T_f = final temperature

T = absolute temperature in Kelvin (K) & T(K) = T°C + 273.15

Boyle's law definition

Boyle's Law is an ideal gas law where at constant temperature; the volume of an ideal gas is inversely proportional to its absolute pressure.

P_iV_i = P_fV_f

where
P_i = initial pressure

V_i = initial volume
P_f = final pressure
V_f = final volume