Rick is 27 years old. Pretend D is David and R is Rick
D+R=81
D=2R
2R+R=81 ---> 3R=81 ---> 81/3=R R=27 3(27)=81 TRY IT!

<em><u>Solution:</u></em>
<em><u>Given system of equations are:</u></em>
8x + 5y = 18 ------- eqn 1
6x + y = -2 -------- eqn 2
Multiply eqn 2 by -5
-30x -5y = 10 ----- eqn 3
Add eqn 1 and eqn 3 so that y terms gets eliminated
8x + 5y = 18
-30x -5y = 10
( + ) --------------
-22x = 28
Divide both sides by -22

Substitute the x value in eqn 1


Answer:
This cannot factor
Step-by-step explanation:
This cannot factor because there is no number that can be factored out of all of the terms.
Answer:
65.56°
Step-by-step explanation:
We know that if we take dot product of two vectors then it is equal to the product of magnitudes of the vectors and cosine of the angle between them
That is let p and q be any two vectors and A be the angle between them
So, p·q=|p|*|q|*cosA
⇒
Given u=-8i-3j and v=-8i+8j


let A be angle before u and v
therefore, 
⇒
Therefore angle between u and v is 65.56°