Answer:
K=21
Step-by-step explanation:
So first we cross multiply
7/a times 7/40 which equals = 28a and 280
Divided both sides by 28.
28a divided by 28 = A. Then 280 divided = 10
So a = 10
%=percent
percent means parts out of 100
20%=20/100
'of' means multiply
20% of 100 units means
20/100 times 100 units=2000/100 units=20 units