A shop has a sale of 25% off all items in stock. If the original price of a dress is £20 what would be its sale price?

25% off means the new price of the item is 75% of the originl price ( 100% - 25% = 75%)

Multiply the original price by 75%:

20 x 0.75 = 15

The sale price is £15

S.P:25x/100

0.25x=20

x=20/0.25

x=80

i got 86 for this

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for the friend request.

when a figure, such as triangle (xyz) is reflected over the line y = x to create x'y'z' the x-coordinates and y-coordinates of the original image (pre-image) will be reversed for the image. (e.g., (x, y) > (y, x)) this means that the pre-image position of the x- and y-coordinates switch places which in turn provides a mirror like image of the original xyz.  

i notice that when i draw a line segment from x to x', that the points are parallel from each other -- they are exactly across from each other and do not intersect with any other points.  

yes, think i would see the same characteristic if you drew the line segment connecting y with the reflecting line and then y' with the reflecting line because of the essence of reflections. because it is a mirror image, each point was effected the same way which leads me to conclude that they same would apply to y and y'.