Carlos has $10 more than jeremy. jeremy has $5 more than michelle altogether they have $80. what part michelle have?

Let Michelle be x.
Jeremy has 5 more than Michelle = x +5
Carlos has 10 more than Jeremy =  (x+ 5) + 10 = x + 15

Together they all have $80

x + (x+5) + (x+15) = 80
x + x + x + 5 + 15 = 80
3x + 20 = 80
3x = 80 - 20
3x = 60
x  = 60/3 = 20

Michelle has x, which is = 20

Michelle has $20.