I have no idea how to do these :(?
Helping with any of them will help They're homework but I was absent and don't remember how to do them from last year.
Page 1:
15) 1/4 y = -1 -3/4 x (1 over 4 times y = -1 - 3 over 3 times x)
16) -10 = -4x +5y
17) -1 = y -4x
18) 0 = -2x -3y +3
Page 2:
13) 7x -y = 3
14) 6x +5y = -20
15) 5x +3y = -3
16) 4x -5y = -5