Воспользуемся формулой квадрата суммы.
sin^2(x+y) + sin(x-y) - sin(x-y)(x+y) / sin(x-y)
(sin(x+y)(sin(x+y) + sin(x-y)-sin(x-y))) / sin(x+y);
sin^2(x+y) / sin(x + y) = sin(x+y)
9.4x -23.5 =7.2 -0.6x -6.5
9.4x +0.6x =23.5 +0.7
10x =24.2
x =24.2/10
x =2.42