Question

A collection of nickels and dimes is worth $6.10. There are 67 coins in all. how many nickels are there?

Answer 1

 Question 1:

 For this case, the first thing we must do is define variables.
 We have then:
 x: number of nickels
 y: number of dimes
 We write the system of equations that adapts to the problem.
 We have then:
 0.05x + 0.10y = 6.10
 x + y = 67
 Solving the system we have:
 x = 12
 y = 55
 Answer:
 there are 12 nickels

 Question 2:

 For this case, the first thing we must do is define variables.
 We have then:
 x: Allan's score
 y: Dave's score
 We write the system of equations that adapts to the problem.
 We have then:
 x + y = 375
 x = 2y-60
 Solving the system we have:
 x = 230
 y = 145
 Answer:
 Dave: 145 Allan: 230