when
Mw*Cw* ΔTw = M(Al) * C(Al) * ΔT(Al)
when we have Mw (mass of water) = 100g
and Cw (specific heat of water) = 4.18
ΔTw (difference in temperature) = (60-Tf)
and M(Al) (mass of Al ) = 80 g
and C(Al) = 0.9
and ΔT (difference in temperature) = (Tf- 5)
as we see here, the water loses heat and the Al will gain it
so, by substitution:
∴ 100 * 4.18 * (60 -Tf) = 80 * 0.9 * ( Tf - 5 )
∴Tf = 51.9 °C