Question

A rectangle is three times as long as it is wide. If the length is decreased by 2 cm and the width is increased by 3 cm, the new rectangle formed has an area of 42 cm2. What are the dimensions of the original rectangle?

A. 9 cm × 3 cm

B. 7 cm × 6 cm

C. 21 cm × 7 cm

D. 15 cm × 5 cm

Answer 1

Can anybody please help?

Answer 2

There are two ways to approach this problem.
The first way is to set up a system of (2) equations for the length and the width, and solve accordingly.
The second way takes advantage of the given answers. You only have to give 4 tries according to instructions.
First eliminate answers where length is not 3 times the width.
That leaves us with three answers to check.
take the first one:
L=9, W=3
Reduce L by 2 and increase W by three to get 7*6=42 bingo, that satisfy the conditions.
If you want, you can check the rest.

Answer 3

Is C the correct answer? @mathmate

Answer 4

For C:
L=21, W=7
The questions says (L-2)*(W+3)=42
Let's check:
(21-2)*(7+3)=19*10=190 does not equal 42, so it is not the right answer.

For your benefit, would you kindly reread my previous post.

Answer 5

it is A!!!

Answer 6

Exactly! Good job!
:)

Answer 7

(L-2)x(W+3) = (9-2) x (3+3) = 42

Answer 8

Thank you so much!

Answer 9

yw!