[3/7x+1/4x+(3/7x+1/4x-15)]-115=x
3/7x+1/4x+3/7x+1/4x-15-115=x
6/7x+1/2x-130=x
6/7x+1/2x-x=130
5/14x=130
x=130÷5/14
x=364