A sample of a gas occupies a volume of 75.0 ml at 30.0 degrees celsius

Use the Ideal gas Law:

PV=nRT

Which rearranged becomes:

V/T = nR/P

So if n (the number of moles of gas) and P (pressure) are constant, you have


\frac {V_1}{T_1} = \frac {V_2}{T_2}


Here you have the initial volume (75 mL) and temp (30 degrees C= 303.15 Kelvin) and final temp (50 degrees C = 323.15 Kelvin), so now you can solve for the final volume. Of course this all assumes that the pressure remains constant - does it?