Question

You are playing a card game with red and black cards where the red cards (r) are worth five points and the black cards (b) are worth ten points. You currently have 11 cards and a total of 70 points. Which system of equations can be solved to find the number of each type of card you have?

Answer 1

11=r+b
70=5r+10b
I use guess and check. Start with all red, then all black, and then try 6 red and 5 black....(the answer is 6 red and 5 black)

Answer 2

trial and error but that will take time so there is a formula for it hope this helps