Brad buys a video game desk for four dollars there was a discount of 20% off what is the sale price

$3.20

Step-by-step explanation:

The total amount is $4 for the video game desk.

100% = $4

10% = $0.40

20% = $0.40 + $0.40 = $0.80

Therefor the the sale price after the 20% discount is:

$4.00 - $0.80 = $3.20

The longest length is 30 cm

Step-by-step explanation:

Mathematically, the perimeter of a triangle is simply the sum of the lengths of its three sides

So, what we have to do here is divide the perimeter in the given ratio to get the side lengths

since 5 is the biggest of the numbers in the ratio, it represents the largest length value

so we have this as;

(3 + 4 + 5) = 12

So that would be;

5/12 * 72

= 5 * 6 = 30