The answer is : D
X/3 =10
We want to get rid of that 1/3 multiplied by the x value , the goal here is to find the x value. So the equation that makes it easier to do so with multiplication is d.
3(x/3)= (10 )3
[ 3 would cancel three in the left side]
[ on the right side 3*10 =30]
Answer is x=30