According to the order of operations multiplication and division are performed before addition and subtraction. Your expression contains two products. Evaluating those gives ...
... 243 + 62 - 28 = n
The order of operations has you evaluate addition and subtraction left to right.
... 305 - 28 = n . . . . . . . the sum of the first two operands
... 277 = n . . . . . . . . . . . the final sum
