Question

A bag contains blue marbles and red marbles, 31 in total. The number of blue marbles is 9 less than 3 times the number of red marbles. How many blue marbles are there?

Answer 1

Answer:21 blue marbles

Explanation:

(3r-9)+r=31

4r-9=31

4r=40

r=10 Red marbles

B+

b+(10)=31

b=21 blue marbles