3.2 Relating Letters to Numbers – Adding and Subtracting

Here is a true statement, 2 + 5 = 7, which we can rewrite either as 5 = 7 – 2 or as
2 = 7 – 5.

Now we do the same with letters: a + b = c which we can rewrite either as b = c – a or as a = c – b.

Can you see how the equations with the letters are exactly the same as the ones written above with numbers, if you replace 2 by a, 5 by b and 7 by c each time?

Here we have a similar situation, first with numbers and then with letters replacing the numbers: