split the coins into three groups, a, b and c consisting of 3 coins in each group.
1. if a=b, the the counterfeit is in group c
weigh any two coins in group c and figure out the rest.
2. if a≠b, then the counterfeit is in the lighter group.
weigh any two coins in the lighter group and figure out the rest.
the answer is c.
so to get the answer add 90+30= 120
then take 180-120=60 (which is your leftover angle)
hello : solutio ( 6 ; 2)
the translation is : x' = x + a *)
y' = y + b **)
calculate the coordinates ( a ; b) of vectro by the translation
you have : x' = -7 y' = 0 x = -6 y = -2
substitute in (*) , (***) : -7 = -6 +a
0 = - 2 + b
a = -1 and b= 2
so : x' = x - 1
y' = y + 2
calculate now the coordinates of the image of the point (7,0) under the same translation.
x = 7 and b = 0
so : x' = 7-1 = 6 and y' = 0 + 2 = 2
the image is : ( 6 ; 2 )