Write the sum and difference using the numbers 6 and a. Find the value of each expression when a = 0; 1.

Let’s write the expression for the sum for the numbers 6 and a: (6 + a) or (a + 6).
Let us find the value of the expressions at a = 0 (substituting the numerical value of a into the expression):
6 + a = 6 + 0 = 6 or a + 6 = 0 + 6 = 6.
Similarly, we calculate the value of the expressions for a = 1:
6 + a = 6 + 1 = 7 or a + 6 = 1 + 6 = 7.

Let’s write the expression for the difference between the numbers 6 and a: (6 – a) or (a – 6).
Let us find the value of the expressions for a = 0 and for a = 1:
at a = 0 6 – a = 6 – 0 = 6
a – 6 = 0 – 6 = – 6
with a = 1 6 – a = 6 – 1 = 5
a – 6 = 1 – 6 = – 5