4 is again c because you should put the 2 here 2a'2-1 so this is 2a'1 and this is 20 so
A2 is 20
Than you should again do this and find a3 ...
Answer:

Step-by-step explanation:







From 

Substitute the value of
and
in 

Since there are 3ft in 1m, multiply the 121 ft2 by 3ft. ( 121 ft2 ×3ft ) -> ( 363 ft3 ) = 363 m2
Step-by-step explanation:
180°= 3q+q+q (Sum of angles in a triangle)
180°=5q
q=180÷5
q=36
Acute angle=36°
Obtuse angle=108°