Answer:
x=-32/29

Step-by-step explanation:
3x+4y=36 Equation 1
-5x+3y=35 Equation 2
Multiplying equation 1 with 3 (value before y in equation 2) and equation 2 with 4 (value before y in equation 1) we obtain equations 3 and 4 as follows
9x+12=108 equation 3
-20x+12y=140 equation 4
Subtracting equation 3 from equation 4 we obtain
-29x=32
x=-32/29
To find the value of y, we substitute the value of x into equation 2 as initially given in the equation
-5(-32/29)=35-3y
-5(-32/29)-35=-3y

Answer is (0,3)
hope it helps
Proving a relation for all natural numbers involves proving it for n = 1 and showing that it holds for n + 1 if it is assumed that it is true for any n.
The relation 2+4+6+...+2n = n^2+n has to be proved.
If n = 1, the right hand side is equal to 2*1 = 2 and the left hand side is equal to 1^1 + 1 = 1 + 1 = 2
Assume that the relation holds for any value of n.
2 + 4 + 6 + ... + 2n + 2(n+1) = n^2 + n + 2(n + 1)
= n^2 + n + 2n + 2
= n^2 + 2n + 1 + n + 1
= (n + 1)^2 + (n + 1)
This shows that the given relation is true for n = 1 and if it is assumed to be true for n it is also true for n + 1.
<span>By mathematical induction the relation is true for any value of n.</span>
As measured by the MAD, the variability ratio is
(MAD of 6th grade heights)/(MAD of 7th grade heights) = 1.2/0.6 = 2.0
The 4th selection is appropriate:
2.0