Answer:
T= 210.15 N
F= 75.31 N
Step-by-step explanation:
Let the tension in string be T newton. 
According to the question 
⇒T×cos21°= mg 
⇒T= mg/cos21°
⇒T=20×9.81/cos21
⇒T= 210.15 N
now, the magnitude of horizontal force 
F= Tsin21°
⇒F= 210.15×sin21°
=75.31 N