PLEASE HELP
Which is the best first step when solving the following system of equations?
y=7x+3
y=9x
A. Multiply the first equation by –7.
B. Substitute 9x for y in the first equation.
C. Multiply the second equation by Negative 3.
D. Substitute 7x for y in the second equation.

B. Substitute 9x for y in the first equation

Step-by-step explanation:

There are various ways of solving a system of linear equations:

- Graphing

- Substitution

- Elimination

Here, given that we have two equations that are equal to y in terms of x, we can use substitution and essentially either plug in the expression (7x + 3) in for y in the second equation or plug in the expression (9x) in for y in the first equation.

Look at the answer choices: only B matches, so it's the correct answer.

Step-by-step explanation:

Step 1:  Find the most reasonable step

Option A:  It doesn't make sense because that will not help us solve the system of equation.

Option B: This option makes sense because you can then solve for x.

Option C:  It doesn't make sense because that will not help us solve the system of equation.

Option D: It doesn't make sense because that will not help us solve the system of equation.

 Option B

37/3

step-by-step explanation:

step 1: simplify both sides of the equation.

7x+8(x+

1

4

)=3(6x−9)−8

7x+(8)(x)+(8)(

1

4

)=(3)(6x)+(3)(−9)+−8(distribute)

7x+8x+2=18x+−27+−8

(7x+8x)+(2)=(18x)+(−27+−8)(combine like terms)

15x+2=18x+−35

15x+2=18x−35

tep 2: subtract 18x from both sides.

15x+2−18x=18x−35−18x

−3x+2=−35

step 3: subtract 2 from both sides.

−3x+2−2=−35−2

−3x=−37

step 4: divide both sides by -3.

−3x

−3

=

−37

−3

x=

37

3