In order to solve this equation, you would first have to subtract the four dollar rental fee from the total twelve dollars she spent. That would leave you with $8. This is so you know how much in total it took per hour, instead of all the money totals combined together.
You then divide the eight dollars by 2 dollars per hour. The result would tell you how many hours she rented the bike for.
Once divided, you recieve the number four. This tells you that she rented the bike for for hours.
The base fee is 4 dollars, and the thing the at changes is x or the hours so the equation is 4 + 2x equals 12. and to solve for x we have to first subtract both sides by 4, getting 2x equals 8 then we divide both sides by 2 to get x equals 4 or 4 hours
