$21.00
let the original price = 100%
then the discount price = 100 - 15 = 85%
divide $17.85 by 85 to obtain 1% then multiply by 100 to obtain original price.
original price = $17.85 × 
= $21
80 = 5 x 4 x 4
they have 4 flavors of icecream
you get this by multiplying all the variables and how many different possibilities each variable can be
so,
5 different syrups (5)
4 different candy toppings (4)
from that you know 5 x 4 x ? = 80
so 5 x 4 = 20, and 20 x 4 = 80
so 4 different flavors of ice cream (4)
In the old aquarium, 3 tablespoons of salt were used for 20 gallons. That's a conversion ratio of
That is, for every gallon of water in the aquarium, there was 0.15 tbsp of salt. So a 50 gallon aquarium, Ill should add
to maintain the salinity.
We can reject the last one: subtracting a non-zero value will result in a smaller value.
So now we have:
<span>2(A + B)
(A + B)2
A2 + B2
If all of them are mulptiplications, then they are all equivalent!
I mean by this, if what you meant is this:
</span>
<span>2*(A + B)
(A + B)*2
A*2 + B*2
If there is no sign, then the multiplication sign is implicit,
and all of these expressions say exactly the same: two of A and two of B.
</span>
