Question

Marla noticed that her friend Ron had three times as many pieces of candy as she did. She told him, "If you give me seven pieces of your candy, we'll have exactly the same number of pieces." Ron responded, "I didn't know that until you mentioned it. But I'll make you a deal: If you can show me how to solve this puzzle using algebra, I'll give you the seven pieces. "One minute later, Ron was shocked to see that Marla had solved it perfectly. Can you do the same?

Answer 1

Marla has 7 and Ron has 21

Explanation:

lets take

no. of candies Marla has as "x"

and no. of candies Ron has will be "3x"

Marla says if Ron gives her seven candies, they will have the same no. of candies

so your equation will be -

x + 7 = 3x - 7 (as Marla gets the candy, Ron loses the candy)

3x - x = 7 + 7

2x = 14

∴x = 7

and 3x = 3 x 7 = 21

YOUR WELCOME

Answer 2

This question seems to be asking for the work, so I put it below.

Anyhow, Marla had 3.5 candies, and Ron had 10.5.

Explanation:

x = 3x - 7 (lets set this as "a") { a = 3x - 7}

x + 7 = 3x -7 + 7

x + 7 = 3x

( x + 7 ) / 3 = 3/3x

( x + 7 ) / 3 = x = *(same as "a") {a}

( x + 7 ) / 3 = 3x - 7

( x + 7 ) / 3 * 3 = ( 3x - 7 ) * 3

x + 7 = 9x - 21

x - x + 7 = 9x - x - 21

7 = 8x - 21

7 + 21 = 8x - 21 + 21

28 = 8x

28 / 8 = 8/8x

3.5 = x

We can plug this back into the original equation and find that it is correct because:

x = 3x - 7

x = 3.5 =====

3.5 = 3( 3.5 ) - 7

3.5 = 10.5 - 7

3.5 = 3.5