
Joseph H. answered 01/26/23
Basketball Coach for New Players
In order to solve this problem, let's represent it with couple of equations we can work our way through. For simplicity, we can represent Amy with A, Brian with B, and Carla with C.
Since we know "Amy and Brian had 1250 cards", our first equation will be:
A + B = 1250
We also know that "Amy and Carla had 830 cards", which we can represent with
A + C = 830
Finally, we are told "Brian had 4 times as many cards as Carla", which we can represent with
B = 4C.
By multiplying our second equation (A + C = 830) by four, we can work to remove C from the picture, making this solvable. Doing so gets us
4A + 4C = 3320
Then, by substituting B for 4C, we get
4A + B = 3320
Now, we can simply subtract our first equation (A + B = 1250) from the one we just created we get
3A = 2070
Simply dividing both sides of the equation by 3 allows us to solve for A,
A = 690
Then, we can use this to help find other solutions, starting with our second equation, meaning A + C = 830 can now be understood as 690 + C = 830. Simply by subtracting 690 from both sides of the equation, we find that C = 140.
Finally, since we already know B = 4C, we simply can multiply 140 by 4, ultimately finding that B = 560.
So, in summary, Amy has 690 cards, Brian has 560, and Carla has 140.