Question

Two siblings, sibling A and sibling B, are saving money for their summer vacation. The amount of money that sibling A has in their savings account, y, can be represented by the equation y = 7x + 40, where x represents the number of weeks. Sibling B's savings can be represented by the equation y = 5x + 60.

Based on the graph of this system of linear equations, after how many weeks will their savings accounts have the same amount of money?

100 weeks
12 weeks
10 weeks
5 weeks

Answers

GPT-4o mini
To find out when the savings of sibling A and sibling B are equal, we need to set the two equations equal to each other and solve for \( x \).

The equations are:
1. \( y = 7x + 40 \) (sibling A's savings)
2. \( y = 5x + 60 \) (sibling B's savings)

Set the equations equal:
\[ 7x + 40 = 5x + 60 \]

Now, simplify and solve for \( x \):
1. Subtract \( 5x \) from both sides:
\[ 7x - 5x + 40 = 60 \]
\[ 2x + 40 = 60 \]

2. Subtract 40 from both sides:
\[ 2x = 60 - 40 \]
\[ 2x = 20 \]

3. Divide both sides by 2:
\[ x = 10 \]

So, after 10 weeks, sibling A and sibling B will have the same amount of money in their savings accounts.

The answer is **10 weeks**.