Calculating partial pressures? HELP

A mixture containing 0.770 mol He , 0.307 mol Ne , and 0.120 mol Ar, is confined in a 10.00-L vessel at 25 C .
a. Caclulate partial pressure of He, Ne, Ar
b. Calculate the total pressure of the mixtures

Please explain how you got the answer thanks!

Dalton Law ideal gas law=PV=nRT Temperature is in Kelvin

Pa=moles of a(RT)/V

Pa=partial pressure of A

Ptotal=Pa+Pb+Pc..

to find the partial pressure of He

PHe=0.770moles(0.08216 L*atm/mol*Kelvin)(298K)/10.0L=1.88 atm

Do now the same to determine the partial pressure of Ne, and Ar then add all partial pressure of the mixture to obtain the total pressure of the mixtures.

Good Luck and Practice.