Piano lessons cost $30 per lesson. Find ordered pairs that represent the total cost for x number of lessons.

Question

Check all that apply.
(–1,–30)
(0,30)
(1,30)
(1.5,50)
(3,90)

Answer 1

To find the ordered pairs that represent the total cost for \( x \) number of piano lessons at a cost of $30 per lesson, we can use the formula:

\[ \text{Total Cost} = 30x \]

where \( x \) is the number of lessons and the first element of the ordered pair is \( x \), while the second element is the total cost.

Let's evaluate the given ordered pairs:

1. (–1, –30):
   \[ x = -1 \quad \text{Total Cost} = 30 \times (-1) = -30 \quad \text{(Valid)} \]

2. (0, 30):
   \[ x = 0 \quad \text{Total Cost} = 30 \times 0 = 0 \quad \text{(Not Valid)} \]

3. (1, 30):
   \[ x = 1 \quad \text{Total Cost} = 30 \times 1 = 30 \quad \text{(Valid)} \]

4. (1.5, 50):
   \[ x = 1.5 \quad \text{Total Cost} = 30 \times 1.5 = 45 \quad \text{(Not Valid)} \]

5. (3, 90):
   \[ x = 3 \quad \text{Total Cost} = 30 \times 3 = 90 \quad \text{(Valid)} \]

Thus, the valid ordered pairs from the list are:

• (–1, –30)
• (1, 30)
• (3, 90)

So the correct answers are:

• (–1, –30)
• (1, 30)
• (3, 90)