I know 12 to 15 i equivalent to 4:5 but how explain or show your work

Acarnival sold tickets for $1.50 for adults and $1.00 for students. there were 54 tickets sold for a total of $70.50. write a system of equations to represent the number of adult tickets, x, and the number of student tickets, y. find the solution and explain what it means. i'll you if you me

1. evaluate 8x(2)y9(-2) for x=-1 and y=2 2. simplify the equation. -() 3. simplify the expression. [tex]\frac{5}{x(-2) y9(5)}[/tex]

Jonathan can type 20 documents in 40 minutes ,and susan can type it in 30 minutes and jack can type it in 24 minutes working together ,how much time will it is take them type the same document