If 89.6 joules of heat are needed to heat 20.0 grams of iron from 30.0°c to 40.0°c, what is the specific heat of the iron in jg?°c jg?°c?

The relation of heat (Q), mass (m), and change of temperature (ΔT) is given by the formula:

Q = m*Cs*ΔT, where Cs is the specific heat of the material.

Then, given than you know Q, m and ΔT, you can solv for Cs:

Cs = Q / (m*ΔT)

Cs = 89.6 J / [20 grams * (40.0°C - 30.0°C) ] = 0.448 J / g * °C.