If y varies drectly with x
and y= 4.5 when x= 2.5,
what is y when x= 12?

You have to figure out what the difference is first , so we can se le that the difference between y and x will always be 2, we got this number by subtracting 4.5-2.5=2.
So we are given x which is 12 so in order to solve this you just substitute x with 2 in the next equation 12+x=y/ 12+2=14

Because 1.5 * 1.5 is 2.25 not 3 1.5 * 2 is 3