# How do you solve by substitution #x + y = 15# and #4x + 3y = 38#?

Enter this expression as an alternative in the second equation:

Then

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Determine the solution by separating one variable from the other and substituting it in the other equation.

and use the second one as a replacement:

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To solve by substitution, rearrange one of the equations to solve for one variable, then substitute that expression into the other equation and solve for the remaining variable. In this case, rearrange the first equation to solve for x or y, then substitute into the second equation and solve for the other variable. Let's solve for y in the first equation: y = 15 - x Now substitute this expression for y in the second equation: 4x + 3(15 - x) = 38 Now solve for x: 4x + 45 - 3x = 38 x + 45 = 38 x = 38 - 45 x = -7 Now substitute the value of x into the first equation to solve for y: -7 + y = 15 y = 15 + 7 y = 22 Therefore, the solution is x = -7 and y = 22.

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