A good app that would help you with math is photomath
I suppose a DJ wants to select 4 different songs, then there are: 12*11*10*9 = 11880 ways to choose them.
If the order of the songs he plays doesn't matter, there are: 
ways to choose them.
So you’re basically multiplying 18 and 15. It’s going to be 270 ft
Answer:
Step-by-step explanation:
2. 9a +4c=43
a+c=7
The total tickets for adults and children = 7 (a+c =7) 7 people in all
price for adult = $9 (9a) Price per child =$4 (4c)
total price =$ 43
9a +7c = 43
Answer:
7/2??
Step-by-step explanation:
Im not sure what you mean but 3 1/2 is the same thing as 7/2
