81.2k views
23 votes
You and your friend collect each rocks and fossils. your friend collects three times as many rocks and half as many fossils as you. you collect 20 objects. your friend collects 20 objects. how many rocks andhow many fossils do you each collect. PLEASE ANSWER FAST! I DONT WANNA FAIL!!

User Nbeyer
by
6.6k points

1 Answer

6 votes

Answer:

  • you - 4 rocks and 16 fossils
  • friend - 12 rocks and 8 fossils

Explanation:

Let the rock be r and the fossil be f

Equations

  • You: r + f = 20
  • Friend: 3r + 1/2f = 20

Double the second equation and subtract the first one:

  • 2(3r + 1/2f) - (r - f) = 2*20 - 20
  • 6r - r = 20
  • 5r = 20
  • r = 4

Then find f:

  • f = 20 - 4 = 16

So you collect 4 rocks and 16 fossils

Friend collects:

  • 4*3 = 12 rocks and
  • 1/2*16 = 8 fossils
User Roman Shamritskiy
by
6.9k points
Welcome to QAmmunity.org, where you can ask questions and receive answers from other members of our community.