Question

Algebra 1!!

Answer 1

Answer: (6, 3)

Explanation: Our first equation tells us that x means the same thing as 2y so we can replace the x in the second equation with a 2y.

Our second equation then becomes 2(2y) + 3y = 21.

If we simplify on the left side we get

4y + 3y = 21 which simplifies to 7y = 21.

Solving from here, we find that y = 3.

To find x, plug 3 back in for y in the first equation

to get x = 2(3) which simplifies to x = 6.

So our answer is (6, 3).

Answer 2

Answer:

$\huge\boxed{b.\ x=6;\ y=3}$

Step-by-step explanation:

$\left\{\begin{array}{ccc}x=2y&(1)\\2x+3y=21&(2)\end{array}\right\\\\\text{Substitute (1) to (2):}\\2(2y)+3y=21\\4y+3y=21\qquad\text{combine like terms}\\7y=21\qquad\text{divide both sides by 7}\\\dfrac{7y}{7}=\dfrac{21}{7}\\\boxed{y=3}\\\\\text{Substitute it to (1):}\\x=2(3)\\\boxed{x=6}$