I'm sorry someone help me out please thank you

How do i do this activity, is appreciated

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.

The edge of a cube was found to be 30 cm with a possible error in measurement of 0.4 cm. use differentials to estimate the maximum possible error, relative error, and percentage error in computing the volume of the cube and the surface area of the cube. (round your answers to four decimal places.) (a) the volume of the cube maximum possible error cm3 relative error percentage error % (b) the surface area of the cube maximum possible error cm2 relative error percentage error %