Step-by-step explanation:
[tex]75.5kg - \frac{ \frac{5}{2}kg }{month} \times (x \: month) = 53kg \\ 75.5kg - 53kg = \frac{ \frac{5}{2}kg }{month} \times (x \: month) \\ 22.5kg = \frac{5}{2} kg \times x \\ \frac{22.5kg}{ \frac{5}{2} kg} = \frac{\frac{5}{2} kg \times x}{ \frac{5}{2} kg } \\ x = 9[/tex]
Therefore, Ronald achieved his goal of 53 kg after 9 months.