Solve using any method 4x-y=20 and -2x-2y=10

Asap the total attendance for all of a baseball league in 2012 was about 7.5×107 fans, while the attendance for the tornadoes in 2012 was about 1.5×106 fans. about how many times more was the attendance for the entire baseball league than the attendance for just the tornadoes? 50 times more 10 times more 2 times more 5 times more

In the polynomial below, what number should replace the question mark to produce a difference of squares? x2 + ? x - 36

Find the domain of the following expression: 1/(√x)-2