During Distributive property, the number on the outside of the parenthesis basically gets multiplied by the numbers inside the parenthesis. In this case, you would multiply 6 by 5 and 4. When you get the products, then follow the sign that comes next. In this case, you would add the products to get a total sum. I attached a photo for further reference.
Hope this helps!
Brrnrb ururrururjbbrejejrjrjjrjrjjrjr rjjrjrjrjr
Given,
567 + x = 1257
=> x = 1257 - 567
=> x = 690
Option c is correct.
Please insert a picture for context