18 - 7 ÷ (1/5 + 1/2)
= 18 - 7/(7/10)
= 18 - 10
= 8

The quotient of 12/7 and 4/9 is 3 6/7.

12/7 * 9/4 = 108/28 = 3 24/28 = 3 6/7; GCF is 4

13 1/4 - 5 9/16
= 53/4 - 89/16
= ((53 × 16) - (89 × 4)) / (4 × 16)
= (848 - 356) / 64
= 492/64
= 123/16
= 7 11/16

Solution:
To solve the expression 77.7 - 12.7 + 1.7, we follow the order of operations (PEMDAS), which states that we should perform the addition and subtraction from left to right.

77.7 - 12.7 = 65
65 + 1.7 = 66.7

Therefore, the correct value for the expression 77.7 - 12.7 + 1.7 is 66.7.

A ball dropped from a certain height rises after bouncing to 2 ft. If this is 15% of its original height, 13.33 feet is the height from which it was dropped.
Solution
Let's assume the original height from which the ball was dropped is represented by "h" feet.

According to the given information, after bouncing, the ball rises to 2 ft, which is 15% of its original height. We can set up the following equation to represent this relationship:

0.15h = 2

To find the value of "h," we can solve this equation:

h = 2 / 0.15

h 13.33 feet

Therefore, the ball was dropped from a height of approximately 13.33 feet.


A shop sells compact disks for $16 per piece. If each disk costs $9 to the shop owner. 77.78% profit percent does the shop owner earn.
Solution
To calculate the profit percentage, we need to determine the profit earned by the shop owner per CD and then calculate it as a percentage of the cost price.

Profit per CD = Selling price per CD - Cost price per CD
Profit per CD = $16 - $9
Profit per CD = $7

Now, let's calculate the profit percentage:

Profit percentage = (Profit per CD / Cost price per CD) * 100
Profit percentage = ($7 / $9) * 100
Profit percentage 77.78%

Therefore, the shop owner earns a profit of approximately 77.78%.