Since addition is commutative, she can add anyway she wants.
(17+51)+(10+13)
(51+10)+(17+13)
Hope this helps.
That bracket symbol, with an r in it, means "the absolute value of r".
So r's absolute value is -2 meaning r is two units from zero
r= 2
y=mx+B is the formula for finding the slop intercept
Largeur = x
longueur = 4 x
2 ( x + 4 x) = 20
2 x + 8 x = 20
10 x =20
x = 2
largeur = 2 et longueur = 8
