I need some help with this one please...

A+B ----> 2 D H= -765.3 kj S= 344 j/k
C ------> D H= 521 kj S= -171 j/k

calculate G at 298 K for A+B ------> 2C

I know I need to use the formula G= H-TS but I don't know how to get the numbers.