So k=katie's' age
m=mara's age
k is 2 times as old as m
k=2m
sum is 24
add means sum
k+m=24
so we have
k+m=24 and
k=2m
subsitute
2m+m=24
add
3m=24
divide both sides by 3
m=8
subsitute again
k=2m
k=2(8)
k=16
katie=16
mara=8
-30, 10*4=40 so you do 9-40+1 which is equal to -30
Answer:
22.5
Step-by-step explanation:
If you divide y/x each ticket costs $2.5, so multiply 2.5x9 and that's your answer. :)
Answer:
.
Step-by-step explanation:
Since repetition isn't allowed, there would be 
choices for the first donut, 
choices for the second donut, and 
choices for the third donut. If the order in which donuts are placed in the bag matters, there would be 
unique ways to choose a bag of these donuts.
In practice, donuts in the bag are mixed, and the ordering of donuts doesn't matter. The same way of counting would then count every possible mix of three donuts type 
times.
For example, if a bag includes donut of type 
, 
, and 
, the count would include the following 
arrangements:
Thus, when the order of donuts in the bag doesn't matter, it would be necessary to divide the count by to find the actual number of donut combinations:
.
Using combinatorics notations, the answer to this question is the same as the number of ways to choose an unordered set of 
objects from a set of distinct objects:
.
.
.
.
.
.
.