To set up the system of equations for Joelle and Lewis based on the information provided:
Let \( x \) represent the number of weeks.
Joelle's equation:
- Joelle starts with 18 rocks and gains 4 each week, so her equation is: \[ y = 4x + 18 \]
Lewis's equation:
- Lewis starts with 30 rocks and gains 3 each week, so his equation is: \[ y = 3x + 30 \]
Now, putting the responses in the correct inputs:
a) Joelle has \( y = 4x + 18 \)
b) Lewis has \( y = 3x + 30 \)
To find out after how many weeks Joelle and Lewis will have the same number of rocks:
Set their equations equal to each other: \[ 4x + 18 = 3x + 30 \]
Solving for \( x \):
- Subtract \( 3x \) from both sides: \[ x + 18 = 30 \]
- Subtract 18 from both sides: \[ x = 12 \]
So, they will have the same number of rocks after 12 weeks.
c) After how many weeks will Joelle and Lewis have the same number of rocks in their collections? 12 weeks
To find out how many rocks they will each have when the amount of rocks in their collection is equal, substitute \( x = 12 \) into either equation. Using Joelle's equation:
\[ y = 4(12) + 18 \] \[ y = 48 + 18 = 66 \]
Using Lewis's equation:
\[ y = 3(12) + 30 \] \[ y = 36 + 30 = 66 \]
So when they have the same number of rocks, they will each have 66 rocks.
d) They will each have 66 rocks in their collection.