The amount of heat needed to increase the temperature of a substance by [tex]\Delta T[/tex] is given by
[tex]Q=mC_s \Delta T[/tex]
where
m is the mass of the substance
Cs is the specific heat capacity of the substance
[tex]\Delta T[/tex] is the increase of temperature of the substance
If we plug the data of the problem into the formula, we find
[tex]Q=(12.5 g)(0.125 cal/g^{\circ}C)(100.0^{\circ}C-20.0^{\circ}C)=125 cal[/tex]
and this is the amount of heat needed to bring 12.5 g of aluminium from 20 degrees to 100 degrees.
