How do I find the mass of liquid water from a graph?

Jun 2017
399
6
Lima, Peru
I'm confused exactly on how should I use the equation for temperature equilibrium. Therefore I need help here.

The problem is as follows:

The graph from bellow shows the change in temperature which experiences two samples of water due their thermic interaction. Find the mass (in kilograms) of liquid water which is obtained in the thermic equilibrium.



The alternatives are as follows:

$\begin{array}{ll}
1.&0.9\,kg\\
2.&1.2\,kg\\
3.&1.3\,kg\\
4.&1.5\,kg\\
5.&1.8\,kg\\
\end{array}$

All I remember for this kind of problem is that the equilibrium is reached when the heat lost by the typically warmer substance is gained by the cooler substance.

But I don't know exactly how to make the right interpretation from the graph which uses temperature versus heat.
Can somebody help me here?.:rolleyes: