For a fixed material, heat is directly proportional to both mass and temperature change.
Start from the base case
The base case needs 30 joules of heat.
Qbase=30 J
Double the mass
Keeping the material and warming the same, doubling mass doubles the heat to 60 joules.
Qmore mass=2⋅30 J=60 J
Double the temperature change
Keeping the mass and material the same, doubling the temperature change also gives 60 joules.
Qmore warming=2⋅30 J=60 J