Answer:
a = 30
Step-by-step explanation:
Given the following data;
a = 18
b = 3
This is a direct proportion question.
Therefore, a is directly proportional to b.
Mathematically, a = kb
First of all we would find the constant, k;
k = a/b
k = 18/3
k = 6
Now to find the value of a when b = 5
a = kb
a = 6*5
a = 30