the formula is : y = mx + b so m is the slope and b is the y-intercept and now you have : 5 = 5/3(3) + b so you need b so you can say :
5 = 5/3(3) + b ⇒ 5 = 5 + b ⇒ 5 - 5 = b so b =0 so in this question we dont have any y-intercept so the answer is : y = 5/3x
but an other formula is : ( y - 5 ) = 5/3 ( x - 3 )
but the standard form is gonna be : y - 5/3x = 0 or 3y - 5x = 0 :))
i hope this is helpful
have a nice day