Compute the following products.
(4x+5)(4x−5)

(4x+5)2

(4x+5)(4x-5) is equal to 16x^2+20x-20x-25
The positive and negative 20x cancel out
Leaving you with: 16x^2 - 25
[S/N this is a pattern that shows up a decent amount. Whenever you have something that looks like (x^2-y^2) it factors out to (x+y)(x-y). It might be helpful to remember]

The next one, (4x+5)2, just follows the distributive property. Multiply both components within the parentheses bye the coefficient of 2: 8x+10

1. $21 divided by 6m= $3.5
2. Take the $3.5 and multiply by 11m =38.5m
3. $28 divide by $3.5=8m