Let's start from the left side, and manipulate it to get the right side, which would prove the identity.
We know that:
i)

ii)

.
From the above fundamental identities, we can rewrite the left hand side as:


,
which is what we needed to show.
$20.70
Step-by-step explanation:
15% of 18 is 2.7 so 18 + 2.7 = 20.70
Answer: 13 minutes
Step-by-step explanation:
( 0 + 2 + 10 + 8 + 20 + 12 + 30 + 7 + 40 + 1)/10 = 130/10 = 13
Hope this helps!