To solve the problem of finding the fifth common multiple of two numbers, given that the first common multiple is 4, we can follow these simple steps:
1. Identify the first common multiple, which is given as 4.
2. To find the fifth common multiple, multiply the first common multiple by 5 because the [tex]\( n \)[/tex]-th common multiple of a number [tex]\( x \)[/tex] is given by [tex]\( n \times x \)[/tex].
Given the first common multiple is 4, the fifth common multiple is calculated as:
[tex]\[ 5 \times 4 = 20 \][/tex]
Hence, the correct answer is:
(d) 20
