There are 360 degrees in a circle. Thus, a 25 degree sector would make up 25/360 of the circle. 25/360 can be simplified to .06944444. This rounds to .07, which is 7%.
8.5b. 7a= 5a +3b -5a -5a 2a = 3b /2 a= 1.5b Solve by substitution and you get; 8.5b=8.5b Because of the lack of constants in the equation there isn't a definite answer.