Question

Can somebody please help me with this problem please

Answer 1

Answer:

m = 3, n = 4

Step-by-step explanation:

Solve using the substitution process. First, start with the second equation:

2m + 2n = 14

Simplify. Divide 2 from all terms within the equation. What you do to one side, you do to the other:

(2m + 2n)/2 = (14)/2

m + n = 7

Isolate the variable m. Subtract n from both sides:

m + n (-n) = 7 (-n)

m = 7 - n

Plug in 7 - n for m in the first equation:

-5m + 9n = 21

-5(7 - n) + 9n = 21

Solve. First, distribute -5 to all terms within the parenthesis:

(-35 + 5n) + 9n = 21

Simplify. Combine like terms:

-35 + (5n + 9n) = 21

-35 + 14n = 21

Isolate the variable, n. Note the equal sign, what you do to one side, you do to the other. Do the opposite of PEMDAS. First, add 35 to both sides:

14n - 35 (+35) = 21 (+35)

14n = 21 + 35

14n = 56

Isolate the variable n. Divide 14 from both sides:

(14n)/14 = (56)/14

n = 56/14

n = 4

Plug in 4 to n in one of the equations, and solve for m.

2m + 2n = 14

2m + 2(4) = 14

2m + 8 = 14

Isolate the variable, m. Do the opposite of PEMDAS. First, subtract 8 from both sides:

2m + 8 (-8) = 14 (-8)

2m = 14 - 8

2m = 6

Divide 2 from both sides:

(2m)/2 = (6)/2

m = 6/2

m = 3

Your answers: m = 3, n = 4

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Answer 2

Answer:

(3, 4)

Step-by-step explanation:

Please include the instructions.  I'm assuming that you want to solve this system of linear equations.

If that's the case, let's use elimination by addition and subtraction.

Multiply the first equation, -5m + 9n = 21, by 2:  -10m + 18n = 42, and

multiply the second equation, 2m + 2n = 14, by 5:  10m + 10n = 70

Next, combine these two "new" equations:

-10m + 18n = 42

10m + 10n = 70

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          28n = 112.  Dividing both sides by 28, we get  n = 4.

Subbing 4 for n in the second equation, we get 2m + 2(4) = 14, or

2m = 6.  Then m = 3, and the solution is thus

(3, 4).