what is solving systems of equations word problems

Question

Kiana and Jacobi each have a collection of identical red and blue marbles. Kiana's collection of 12 red marbles and 8 marbles weighs 68 grams. Jacobi's collection of 20 red marbles and 12 blue marbles weighs 108 grams. How much do the red marbles weigh?

Answer 1

12r+8b=68

20r+12b=108

simplify each equation

3r+2b=17

5r+3b=27

multiply the first equation by 3 and multiply the second equation by 2

9r+6b=51

10r+6b=54

subtract the first equation from the second equation

r=3 grams is the weight of the red marbles (4 grams for the blue ones)