Answer:
The weight of the package is 1 kilograms.
It will cost  $ 13 by both the couriers services.
Step-by-step explanation:
Let the weight of her package is x kilograms
Now, according to the question:
The charges of first Courier = $10 + $3(x)
and The charges of Second  Courier = $7 + $6(x)
Also, for x  kilograms, both the charges are equal
⇒ $10 + $3(x)  =  $7 + $6(x)
or, 10 + 3x = Â 7 + 6x
or, 10 -7 = 6x - 3x
⇒ 3x = 3, implies  x = 3/3 = 1
⇒ The weight of the package is 1 kilograms.
It will cost : Â 10 + 3(1) = $ 13 Â = 7 + 6(1) by both the couriers services.