Agroup of 25 students want to see a drake concert. tickets for members of drakes fan club cost $20 and tickets for no members cost $25. the total cost is $550

Not drake!

m=number of members
n=number of nonmembers
n+m=25

cost=550=20m+25n
simplify by dividing by 5
110=4m+5n

so we have
n+m=25 and
5n+4m=110
multiply first eequation by -4 and add to second equation

-4n-4m=-100
5n+4m=110+
n+0m=10

n=10
subsitute
n+m=25
10+m=25
m=15

15 members
10 non-members