X^2+x-30 -- find two numbers that add to one and multiply to -30, which would be 6 and -5. so now you have x^2+6x-5x-30. factor out x and 5 to get x(x+6)-5(x+6). so you get (x+6)*(x-5)
6r - 3t = 6 /*8
6r + 8t = - 16 /*3
48r - 24t = 48
48r + 24t = - 48
---------------------- +
96r = 0
r = 0
t = ( -16 + 6r)/8 = - 16/8 = - 2
It will be 165.85365853658536. Hope this helps !!
