"2 more than" means that there will be a + 2 in the equation. "3 times a number" means that 3 is multiplied by an unknown number which can be represented by a variable such as x. "At most" means less than or equal to, since the number cannot be greater than.
So generally, you might want to write the equation as 2 + 3x ≤ 53, but 2 + 3x is not in y = mx + b form. Basically, you need to write it as 3x + 2 ≤ 53 because that's how math works.
