Here we discuss about the Subtraction of Literals.
If we are asked to subtract 5 from 6, then we write 6 – 5. ( whatever number is there after from that we have to write first). When we are asked to subtract a number say 2 from a literal a, we write a – 2 and is read as ‘a minus 3’. Note that a – 3 can also be read as ‘3 less than a literal number a’.
Similarly, if b is subtracted from a, we write a – b. We can also read a – b as ‘b less than a’.
If a is subtracted from b, then we write b – a. (a – b) – c means that b is subtracted from a and then c is to be subtracted from the result. We can also say that c is subtracted from the difference of b from a.
It should be noted that Commutativity and Associativity of subtraction are not true for literals as they are not true for numbers.
Write each of the following phrases using numbers, literals and the basic operation of subtraction:
(i) 4 less than a literal y Solution: y - 4
(ii) Decrease b by 6 Solution: b - 6
(iii) Subtract 3 from c Solution: c - 3
(iv) y less than the sum of z and 7 Solution: y - (z + 7 )
(v) Decrease the sum of x and y by z Solution: (x + y) - z