PLEASE HELP
when x=21, y=5. find x when y=25

This is a simple ratio. x : y.  So x = 21 when y = 5.

21 : 5.

x : 25

So you are timesing each side by 5

So 21 x 5 = 105.

x = 105

when x is 21 and y is 5 means that y*4.2=x ( bc 21:5=4.2) so to find x u have to multiply y*4.2

Step-by-step explanation:

21/5 = 4.2

25*4.2 = 105

there are lots of ways.   pick's theorem tells us if the vertices are lattice points the area a is

a = b/2 + i - 1

where b is the number of boundary lattice points and i is the number of interior lattice points.

in the figure i count b=16, i=50 so

a = 8 + 50 - 1 = 57

let's try the shoelace formula.   the area is half the sum of the cross products of the sides.  

a(-2,6)   -2(2)-6(-5) = 26

b(-5,2)   -5(-3) - 2(-2) = 19

c(-2,-3) -2(-3) - (-3)(4) = 18

d(4,-3)   4(3) - (-3)(5) = 27

e(5,3)   5(3) - 3(1) = 12

f(1,3)     1(6) - 3(-2) = 12

a(-2,6)

each of the cross products is twice the area of the triangle with the associated side and one vertex the origin. so the area of abo=26/2=13.

area = (1/2) (26 + 19 +   18 + 27 + 12 + 12) = 57

that checks!