Posted by Josh on .
The area of a rectangle is 90m 2. The base is three less than three times the height. What is the perimeter?

Math 
Damon,
b = 3 h 3
area = b h = (3 h  3)h = 3 h^2  3 h = 90
so
3 h^2  3 h  90 = 0
(h+5)(3h18) = 0
h = 6 is positive real solution
so
b = 3*6 3 = 15
then perimeter = 2 h + 2 b 
Math 
Josh,
dont get it

Math 
Josh,
how did you get that. not rudely.

Math 
PsyDAG,
Let B = base and H = height
From the first sentence:
B * H = 90
From the second sentence:
B = 3H  3
Substitute the value of B from the second equation into the first and solve for H. Put the value of H in the second equation to find B. Check by putting both values into the first equation.
As Damon says, "then perimeter = 2 h + 2 b".
I hope this helps. Thanks for asking.