At the BOBA CLUB you must be a member to buy boba. A membership cost $4. Once you are a member of BOBA CLUB each Boba drink is $2. At JACK’S BOBA you do not need to be a member. Anyone can walk in JACK'S BOBA shop and buy one drink for $3

Boba Club: y=2x+4
Jacks Boba: y=3x

Which is cheaper if you want to buy 7 boba drinks? How much cheaper? What is the solution to the system of equation?