Because of PEMDAS you would answer 6-4 first in the equation 5x(6-4) because it is in parentheses. Since there are no parentheses in 5x6-4 you would multiply 5x6 first.
The expressions 5 x (6 - 4) and 5 x 6 - 4 are different because....
Anything inside the parentheses has to be done first so 5 x (6 - 4) the 6 -4 has to be done first but in 5 x 6 - 4 you have to follow PEMDAS and do multiplication first.
