Answer:

Step-by-step explanation:
we are given

we can simplify left side and make it equal to right side
we can use trig identity


now, we can plug values

now, we can simplify



now, we can factor it

![\frac{(sin(a)+cos(a))[3-4(sin^2(a)+cos^2(a)-sin(a)cos(a)]}{sin(a)+cos(a)}](https://tex.z-dn.net/?f=%5Cfrac%7B%28sin%28a%29%2Bcos%28a%29%29%5B3-4%28sin%5E2%28a%29%2Bcos%5E2%28a%29-sin%28a%29cos%28a%29%5D%7D%7Bsin%28a%29%2Bcos%28a%29%7D%20)
we can use trig identity

![\frac{(sin(a)+cos(a))[3-4(1-sin(a)cos(a)]}{sin(a)+cos(a)}](https://tex.z-dn.net/?f=%5Cfrac%7B%28sin%28a%29%2Bcos%28a%29%29%5B3-4%281-sin%28a%29cos%28a%29%5D%7D%7Bsin%28a%29%2Bcos%28a%29%7D%20)
we can cancel terms

now, we can simplify it further




now, we can use trig identity

we can replace it

so,

7/8=0.875
0.875 x 40= 35
Therefore, Kris has finished 35 questions.
Hope this helps.
Answer:
A rational number is said to be closed if the subtracted values and the result obtained are rational. Hence, the equations which supports the condition are :
5.5 - 0.5 = 4
5√4 - √4 = 4√4
Step-by-step explanation:
A.)
√8 - √8 = 0 ; the added values aren't rational and the result, Zero is not rational either.
B.)
5√4 - √4 = 4√4
5(2) - 2 = 2(2)
10 - 2 = 4
All the values in the expression are rational ; hence, it supports the assertion.
C)
5.5 - 0.5 = 4 ; all the values in the expression are rational, hence, it supports the fact.
2√3 - √3 = √3 ; the values in the expression are not rational, hence, it does not meet the condition.
Therefore, only options B and C supports the assertion.
Let me add that I learned most of this from Brainly a user named fichoh :)
Rational numbers are numbers that can be turned into a fraction. They can be negative or positive.
Integers are whole numbers. They can be negative or positive.
Numbers such as 0.10 are rational because they can be turned into a fraction
0.10 = 1/10....and since it is not a whole number, it is not an integer.