Dylan works out and burns 10 calories per minute swimming and 7 calories per minute biking. He wants to burn a minimum of 600 calories. Due to daylight limitations, the time Dylan spends swimming must be no less than twice the time he spends biking.

He must bike at least 22.2 minutes and swim at least 44.4.

Let x be the amount of time he spends biking. Since he must swim no less than twice as much as he bikes, 2x will be the amount of time he swims.

2x (10) + x (7) represents the amount of calories he burns; 10 calories per minute swimming (2x) and 7 calories per minute biking (x).

2x (10) + x (7) ≥ 600

20x + 7x ≥600

27x≥600

Divide both sides by 27, and we have

x ≥ 22.2

This means he must bike 22.2 minutes, and swim 2 (22.2) = 44.4 minutes.