In this scenario, you need to understand what it means when y varies directly with x. Since they vary directly, as x increases, so does y. The proportion, also known as factor, stays constant no matter what you plug into x. This is fit by the following equation:
y=x
In other words, if you plug 5 into x, y should always no matter what be three times larger than x (just an example).
To solve this scenario, you need to find a proportion to use with your y = x formula. You can find the proportion by dividing y=72 by x=6.
72/6=12
Now, to use 12 in the formula. Remember that y is 12 times larger than x when you plug a number for x, so to make y larger, multiply 12 and x.
y=12x
let(x)→6
Plug 6 into x.
Therefore, y = 72 when x = 6.
y=12(6)=72