203,164 views
30 votes
30 votes
If you give me 70 coins I will have three times as much money as you, but if I give you 70 coins, then you will have five times as much as me. How many coins do we each have?​

User Jengar
by
2.9k points

1 Answer

19 votes
19 votes

Answer:

  • I have 110 coins, you have 130 coins

Explanation:

I have x coins and you have y coins.

According to question we set the following equations.

If you give me 70 coins I will have three times as much money as you:

  • x + 70 = 3(y - 70) ⇒ x + 70 = 3y - 210 ⇒ x = 3y - 280

If I give you 70 coins, then you will have five times as much as me:

  • y + 70 = 5(x - 70) ⇒ y + 70 = 5x - 350 ⇒ y = 5x - 420

Solve by substitution:

  • y = 5(3y - 280) - 420
  • y = 15y - 1400 - 420
  • 15y - y = 1820
  • 14y = 1820
  • y = 1820/14
  • y = 130

Find the value of x:

  • x = 3*130 - 280
  • x = 390 - 280
  • x = 110
User Chris Biscardi
by
2.8k points