25% because 21 is a quarter of 84. And 21 times 4= 84, so 21 is 25% of 84.
$520
First, you multiply 26 by 4.
Then you multiply the product (104) by 5.
Factor the numerator to get:
(-3z(z+5))/(z+5) now you notice that (x+5) cancel out leaving:
-3z
You would do
51-5= 46
then you would divide
46/2= 23
so Susan is
23+5=28
Susan is 28 years old and her sister is 23
28+23=51
