Answer:
120
Step-by-step explanation:
The number of ways to select things from a group of things is given by the combination formula.
Where n! means n*(n-1)*(n-2)....
- There are 10 total books, so n = 10
- you have to choose 3 books, so r = 3
Plugging these into the formula gives us:
Hence, there can be 120 different groups of 3 books that u can choose from 10 books total.
y = total cost used.
x = additional minutes
y = $49.95 + $0.15x
$61.20 = $49.95 + $0.15x. Subtract the $49.95 from each side.
$11.25 = $0.15x. Divide each side by $0.15
75 = x.
Michael used 75 additional minutes.
You must first find a common denominator.
Change the fractions to the common denominator.
Then you add or subtract the fractions.
Finally, you may need to reduce the fraction.
Example 1:
Add
1/5 + 1/3
The least common denominator is 15.
Both denominators must become 15.
1/5 + 1/3 = 3/3 * 1/5 + 5/5 * 1/3 = 3/15 + 5/15 = 8/15
Example 2:
Subtract
3/8 - 1/3
The least common denominator is 24.
3/3 * 3/8 - 8/8 * 1/3 = 9/24 - 8/24 = 1/24
Both in addition and subtraction, you only add or subtract the numerators. The denominator of the answer is the common denominator.