A closed cylinder of gas with fixed shape has a pressure p1 at 20.0oC. To what temperature in degrees Celsius would the temperature have to be increased for the pressure to become 1.7 p1?

P V = n RT

V constant
n constant
R constant
so
P / T = constant
T1 = 20 + 273 = 293
p1/ 293 = 1.7 p1 / T2
T2 = 1.7 * 293 = 498 degrees Kelvin
498 - 273 = 225 degrees Celsius