Someone me with this i’m so confused and explain

The school that imani goes to is selling tickets to the annual dance competition. on the first day of the ticket sales the school sold 7 adult tickets and 5 child tickets for a total of $96. the school took in $40 on the second day by seling 3 adult tickets . find the price of an adult ticket and the price of a child ticket. solve by using substitution elimination college prep algebra math heres the 2 equations i came up with 7x+5y=96 and 3x+2y= -40 show all workiv be stuck on this.

Which value of m will create a system of parallel lines with no solution? y = mx - 6 8x - 4y = 12

X^2/100+y^2/25=1 the length of the major axis is: a)5 b)10 c)20