Question

2. A boy and his father played 26 games of checkers. For every game the boy lost, he gave his father 5 cents. For every game the boy won, his father gave him 8 cents. When all the games were played, neither had won nor lost anything. The number of games the boy won i

Answer 1

Answer: the boy won 10 games

Explanation:

Let's call B as the number of games won by the boy, and F as the number of games won by the father.

We know that, there is a total of 26 games:

B + F = 26.

We know that in each game won by the boy, he wins 8 cents, for every game that the father wins, the boy losses 5 cents, and we know that at the end of the 26 games, the boy did not win or lose any money, so we have:

B*8 + F*(-5) = 0.

Then we have a system of equations:

B + F = 26

8*B - 5*F = 0.

The first step is isolating one of the variables. Let's start isolating F in the first equation:

B + F = 26

F = 26 - B.

Now we can replace this in the second equation:

8*B - 5*F = 0

8*B - 5*(26 - B) = 0

8*B + 5*B - 5*26 = 0

13*B = 5*26

B = 5*26/13 = 5*2 = 10

So the boy won 10 games (then the father won the other 16 games)