Following the order of operations, we first solve the problem in parentheses:
3+5x4÷936x4(7+80)x4÷7 = 3+5*4÷936*4*87*4÷7
As there are no exponents, we work on the multiplication/division, in order:
3+5*4÷936*4*87*4÷7 = 3+20÷936*4*87*4÷7
= 3+(5/234)*4*87*4÷7
= 3+(10/117)*87*4÷7
= 3+(870/117)*4÷7
= 3+(3480/117)÷7
= 3 + (3480/819)
= 5937/819