civonamzuk

CX = 1/4(AX)

BX / AX = CX / BX

Kai folded x + 21 starts

Dinny folded x + 39 starts

(x + 21)/(x + 39) = (3/7)/(4/7)

x = 33

Kai folded 54 starts

Spencer paid = 2x/9

Nigel paid      = 5/8(2x/9)

2x/9 + 5/8(2x/9) = 793

x = 2196

Hence, Greta paid $1403

xz/yz=zy/xy=1/2  Incorrect!!!  

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1/       XZ/XY = YZ/XY = 1/2    Correct!!!       X(-5, -13) 

2/      XZ/YZ = XY/YZ = 1/2     Correct!!!       X(-1/2, 2) 

3/      XY/XZ = YZ/XZ = 1/2     Correct!!!       X(4, 17) 

All three above cases are correct but, as you can see, the coordinates of X are not the same!

You need to pick one. 

In the FreeWheelin' Skate Shop, exactly 1/4 of the skateboards are red and exactly 2/3 of the scooters are red. If there are equal numbers of red skateboards and red scooters in the shop, what fraction of the total skateboards and scooters together are red?

The fraction is 4/11     (See diagram))

Your question doesn't make sense. 

3/8 of a triangle is shaded.