1 nickel is 5c, 1 dime is 10 c, 1 quarter is 25 c. 
Let number of nickels be n. Seven less nickels than dimes, so, 
number of dimes is n + 7. Five less dimes than quarters, so, 
number of quarters is n + 12. 
Multiply number of each type by each value and total will be the tips received. 
5n + 10(n + 7) + 25(n + 12) = 40n + 370 = 610 
40n = 240 
Number of nickels was 6 and their value was 30 c 
Number of dimes was 13 and their value was 130 c 
Number of quarters was 18 and their value was 450 c