Question

The value of y varies directly with x If x equals 3 than y equals 21 what is the value of c when the value of y equals 105

Answer 1

If y and x varies directly we can use a rule of 3 to find the missing x so:

$\begin{gathered} 3\to21 \\ x\to105 \end{gathered}$

and the equation will be:

$\begin{gathered} x=\frac{3\cdot105}{21} \\ x=15 \end{gathered}$