Answer:
t = 2.4n
Explanation:
y = mx + c
t = mn + c
c = y-intercept (where the graph line crosses the cost line)
c = 0
mx/mn= gradient ( rise/run, up/across)
mn= 12/5 ( you could have picked any point in the graph )
mn= 2.4
the m is unnecessary now so we discard it
t = 2.4n + 0