Question

7. There are 19 red marbles for every black marble. If there are 120 marbles in the bag, how many red marbles are there? Explain or show your reasoning.

Answer 1

114 marbles.

Explanation:

Let the number of red marbles be r

Let the number of black marbles be b

Given the following data;

Total number of marbles = 120

Translating the word problem into an algebraic equation, we have;

`r = 19b` .......equation 1

`r + b = 120` ........equation 2

Substituting the value of "r" into equation 2, we have;

`19b + b = 120`

`20b = 120`

`b = \frac {120}{20}`

b = 6 marbles.

To find the number of red marbles;

From equation 1;

`r = 19b`

Substituting the value of "b" into equation 1, we have;

`r = 19*6`

r = 114 marbles.

Therefore, there are 114 red marbles in the bag.