Three friends, Nakobe, Mikah, and Ashton, are saving up money to buy microphones for their podcast. The total cost of the microphones is represented by the expression 7x2 − 2x + 11.
The friends have already saved the following amounts:
Nakobe: x2
Mikah: x − 15
Ashton: 5x + 2
Which expression represents the amount of money the friends still need to buy the microphones?