Respuesta :

Answer:

22

Step-by-step explanation:

£9.90 = 990p

x is number of 50p stamps

2x* 20 + x* 50 = 990

40x+50x = 990

90x = 990

x = 11

2x = 22

11 50p stamps

22 20p stamps

check:

11*50+22*20 = 550 + 440 = 990