To find the value of ‘a’ that varies jointly with ‘b’ and ‘c’, we can use the formula for joint variation:
a = k * b * c
where:
- a is the value we want to find,
- k is the constant of variation,
- b and c are the given values.
In this problem, we know:
- k = 3,
- b = 7,
- c = 9.
Substituting these values into the equation, we get:
a = 3 * 7 * 9
Now, perform the multiplication:
a = 3 * 63
Calculating that gives:
a = 189
Therefore, the value of ‘a’ when ‘b’ is 7, ‘c’ is 9, and the constant of variation is 3 is 189.