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Solve the system by substitution.

{:[x=-3y+7],[-4x-5y=7]:}

Solve the system by substitution.\newlinex=3y+74x5y=7 \begin{aligned} x & =-3 y+7 \\ -4 x-5 y & =7 \end{aligned}

Full solution

Q. Solve the system by substitution.\newlinex=3y+74x5y=7 \begin{aligned} x & =-3 y+7 \\ -4 x-5 y & =7 \end{aligned}
  1. Substitute xx in second equation: Substitute the expression for xx from the first equation into the second equation.\newlineGiven the first equation x=3y+7x = -3y + 7, we can substitute this into the second equation 4x5y=7-4x - 5y = 7.
  2. Perform substitution: Perform the substitution.\newlineSubstitute x=3y+7x = -3y + 7 into 4x5y=7-4x - 5y = 7.\newline4(3y+7)5y=7-4(-3y + 7) - 5y = 7
  3. Distribute and simplify: Distribute 4-4 across the terms in the parentheses.\newline4×3y+4×75y=7-4 \times -3y + -4 \times 7 - 5y = 7\newline12y285y=712y - 28 - 5y = 7
  4. Combine like terms: Combine like terms. \newline12y5y28=712y - 5y - 28 = 7\newline7y28=77y - 28 = 7
  5. Isolate y term: Add 2828 to both sides of the equation to isolate the term with yy.\newline7y28+28=7+287y - 28 + 28 = 7 + 28\newline7y=357y = 35
  6. Solve for y: Divide both sides by 77 to solve for y.\newline7y7=357\frac{7y}{7} = \frac{35}{7}\newliney=5y = 5
  7. Substitute yy in first equation: Substitute the value of yy back into the first equation to solve for xx.x=3y+7x = -3y + 7x=3(5)+7x = -3(5) + 7
  8. Calculate xx: Perform the calculation to find the value of xx.x=15+7x = -15 + 7x=8x = -8
  9. Write solution as ordered pair: Write the solution as an ordered pair (x,y)(x, y).\newlineThe solution is (8,5)(-8, 5).

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