Question

A bag contains white marbles and blue marbles, 79 in total. the number of white marbles is 6 less than 4 times the number of blue marbles. how many white marbles are there?

Answer 1

Let x be the number of white marbles and y be the number of blue marbles.
So,
`x+y=79`
Also,
`x = 4y-6` since "the number of white marbles is 6 less than 4 times the number of blue marbles"
We will solve the above system o two equation:
Using the value of x from the second equation in the first equation we get:

`(4y-6)+y=79\\5y=79+6\\5y=85\text{ then }y=(85)/(5)=17\\x=79-17=62`
Conclusion: there is 62 white marbles and 17 blue marbles.