1) -5/3-7/4-5=x/3
-5-21/4-15=x
x=-20-5-1/4=-(25+1/4)
2) 4x^2-12x+9-25+20x-4x^2+7x-21=20
15x=20+21+16
x=57/15=19/5
3) 5x^2-15x-4x-5x^2=6x-16
-19x=6x-16
16=25x
x=16/25
4) (3x-2)(4x+3)-(4x+7)(9+3x)=5x+3
12x^2+x-6-12x^2-57x-63=5x+3
-56x-69=5x+3
-72=61x
x=-72/61