<image>In active response to the call of the Central Committee to support the earthquake relief efforts in the Wenchuan area after the 5•12 earthquake, the Yijia factory worked overtime day and night, planning to produce m tents for the disaster area. The relationship between the remaining production task y (tents) and the production time used x (hours) is shown in the figure.
(1) Find the relationship equation between the variables y and x;
(2) Determine the value of m.