1) 5 ( x + 7 ) - 10 = 50 => 5 ( x + 7 ) = 60
=> x + 7 =12
=> x = 12 - 7
=> x = 5
2) 42 : x - 5 = 1
=> 42 : x = 6
=> x = 7
3) ( x-1 ) ( x- 4 ) = 5
=> x = - 0,1925.....
4) 7x + 8x - 5x = 70
=> 10x = 70
=> x = 7
5) 4x + 9x - x = 60
=> 12x = 60
=> x = 5
*)5(x+7)-10=50
5(x+7)=60
x+7=12
x=5
*)42:x-5=1
42:x=6
x=7
*)7x+8-5x=70
x(7+8-5)=70
10x=70
x=7
*)4x+9x-x=60
x(4+9-1)=60
12x=60
x=5