Answer:
the awnser is 94 because 5×20=100-6=96
To solve -7y > 161, we divide both sides by -7 and we get y < -23. The inequality sign flipped because we divided both sides by a negative number.
To solve 7y > -161, we divide both sides by 7 and it leads to y > -23. The inequality sign does not flip in this case, because we are not dividing both sides by a negative number.
The similarities is that we end up with -23 on the right side, but the inequality signs are different.
Answer: the maximum number of drinks Liam can buy is 4 without over exceeding his price limit.
work:
$3.50 for 5 tacos is $17.50
9 - 5 tacos = 4 drinks
4 drinks x $2 = $8
$17.50 + $8 = $25.50 out of $30 price limit
It's a value you should probably memorize:
You can derive it using some trigonometric identities, other known values of cosine, and properties of the cosine function. For example, using the double angle identity for cosine:
If 
, then
and you probably know that 
, so
When we take the square root, we should take the positive root because 
whenever 
:
