The answer to your problem will be 16
Mike ($3.75): x
Friends ($3.75): 3x
Mike + Friends ≤ 25
3.75(x) + 3.75(3x) ≤ 25
3.75x + 11.25x ≤ 25
15x ≤ 25
≤ 
x ≤ 1
Answer: they can rent the paddleboards for 1 hour 40 minutes
40 * 50= 2,000
Easy way to find this out!
4*5=20.
You take the 0 from 40 and the 0 from 50 and you have
20 +0 zeros.
2000 which is 2,000!