Given a wire with a cross section of. 45cm^2, a length of 3cm, and an internal resistance of 3 ohms, show your 5 steps to solve for the resistivity of the wire

Resistance ∞ (proportional) length

resistance ∞ 1 / area

therefore,

(the constant that we take is known as the resistivity)

resistance = (resistivity*length) / area

resistivity = (resistance * area) / length

= (3 * 45) / 3 = 135/3 = 45 Ωm

in short your answer is 45 Ωm