A) it takes 47.0j to raise the temperature of an 10.7g piece of unknown metal from 13.0∘c to 25.0∘c. what is the specific heat for the metal?
b) the molar heat capacity of silver is 25.35 j/mol⋅∘c. how much energy would it take to raise the temperature of 10.7g of silver by 15.2∘c?
c) what is the specific heat of silver?

The heat Q can be evaluated as:
Q=mcΔT
where:
m is the mass
c specific heat
ΔT change in temperature.
So:
a)
47=10.7c(25-13)
c=0.39 J/g°C
Using the same idea you get (I transformed g into moles using the molar mass of silver from the table of elements):
b) Q=(10.7/107.9)×25.35×15.2=38.21 J
where: Molar mass of Ag = 107.8682 g/mol
c) 38.21=10.7c15.2
c=specific heat of silver=0.235 J/g°C