A letter, which is how you name it. If that is what your asking, of course.
TheProfessor35's answer is correct, but here's a step by step as you asked. PEMDAS stands from Parentheses Exponents Multiplication Division Addition Subtraction. So, in the problem, you first solve the part inside the parentheses. Are there exponents? No, so we move on. Anything need to be multiplied? Yes, 20.3 x 0.7. That gives us 14.21. Now, there is nothing left in the parentheses to be divided, added, or subtracted, so we move on to the outside. We multiply 14.21 by 7 and get 99.47.
68-11=57 (Yesterday's temperature)
That's the expression. ^^ And yesterday's temperature is 57 because, 68 degrees (Today's temperature) minus 11 degrees (how many degrees colder it was yesterday) is equal to 57 degrees (Yesterday's Temperature).
