Answer:
Step 1
Step-by-step explanation:
Mark simplified 3/5 + 5/8 using the steps below:
Step 1: 3/5 * 8/5
Step 2: 3 * 8 / 5 * 5
Step 3: 24/5
Step 4: 4 4/5
Mark's error is in Step 1 where he changed the addition sign to multiplication sign.
The correct solution is:

Answer:
B ($9.78)
Step-by-step explanation:
Number of items an online shopping site sold per second = 420
Number of items it will sell in 30 minutes =
30 minutes = 1800 seconds
Number of items it will sell in 1800 seconds =
= 1800 × 420
= 756,000
∴ This online shopping site will sell 756,000 in 30 minutes .
Y = x² - 3x - 18
When y = 0,
x² - 3x - 18 = 0
<span>(x + 3)(x - 6) = 0
</span>
x = -3 or x = 6