Question

A bag contains white marbles and red marbles, 20 in total. The number of white marbles is 5 more than 2 times the number of red marbles. How many white marbles are there?

Answer 1

15

Explanation:

let r represent red marbles then white = 2r + 5 and total is 20, thus

r + 2r + 5 = 20 ( subtract 5 from both sides )

3r = 15 ( divide both sides by 3 )

r = 5 ← number of red marbles

Thus number of white = 20 - 5 = 15