Please help me :( in chem

Question

A gas sample contains 1.44 moles at 21° C exerts a pressure of 300. torr. Some gas is 

added to the same container and the temperature is increased by 40° C. If the pressure increases 

to 750 torr, how many moles of gas were added to the container? Assume a constant- volume container

Answer 1

PV = nRT

(P1/n1T1) = (P2/n2T2) (V does not change; R does not change)

21 C + 273 = 294K 61 C + 273 = 334K

(300torr)/(1.44 mole)(294K) = (750 torr)/(n2)(334K)

Solve n2 to find number of moles total, then subtract from that the original number of moles (1.44 mole) to obtain the number of moles added.