To compare the memberships from Gym A and Gym B, we want to find the cost per month and see which one is cheaper over a year (12 months).
Gym A:
- Cost for 5 months: $50
- The cost per month (k) would be: \[ k_A = \frac{50}{5} = 10 \]
- Cost for 12 months: \[ y_A = k_A \times 12 = 10 \times 12 = 120 \]
Gym B:
- Cost for 3 months: $40
- The cost per month (k) would be: \[ k_B = \frac{40}{3} \approx 13.33 \]
- Cost for 12 months: \[ y_B = k_B \times 12 = \frac{40}{3} \times 12 = 160 \]
Now we compare the total costs for both gyms over 12 months:
- Total cost at Gym A for 12 months: $120
- Total cost at Gym B for 12 months: $160
Since $120 (Gym A) < $160 (Gym B), Gym A is the cheaper option.
The value of \( k \) for the cheaper membership (Gym A) is:
\[ k = 10 \]
Therefore, the value of \( k \) for the cheaper membership is \( \boxed{10} \).