First make a table
1 4.9
2 14.7
3 24.5
Now find the pattern
To do that, subtract the second one from the first one
14.7-4.9=9.8
Check if it works for the second one
14.7+9.8=24.5
It does now use it
there are 5 seconds between 7 and 12 so 5*9.8=49
49 is your answer!!
(trust ElectricPavlov more than me)
+75 