12(3w+8)=25
36w+96=25 ( I used the distributive property)
-96 . -96
36w=-71
w=-1.972222.... ( I divided both sides by 36)
So I would first find out when they are equal then do one more than that. 21x=18x+45, 3x=45, x=15 so the answer would be 16 jerseys
Subtract the fee from the total:
131- 35.50 = 95.50
Now divide that by the price per mile:
95.50/ 0.40 = 238.75
They drove 238.74 miles

so... notice the example there, with 8
so.. you tell us, what is the relationship then?