Below is an instruction that describes a task. Write a response that appropriately completes the request in Swahili. Please answer in Swahili.

### Instruction:
Jordan is a hockey goalie. In the first period of a game, he blocked four shots. In the second period, he blocked twice as many shots. In the third period, he blocked three fewer than in the second period. When the game ended after the fourth period, he had blocked 21 shots in all. How many did Jordan block in the fourth period?

### Response:
 Hebu F iwe idadi ya mashuti ambayo Jordan alizuia katika kipindi cha nne.
Katika kipindi cha pili, alizuia mashuti 2 * 4 = <<2*4=8>>8.
Katika kipindi cha tatu, alizuia mashuti 8 - 3 = <<8-3=5>>5.
Katika mchezo mzima, alizuia mashuti 4 + 8 + 5 + F = 17 + F = 21.
Hivyo, Jordan alizuia F = 21 - 17 = <<21-17=4>>4 mashuti katika kipindi cha nne.