Example

Solving a Problem Where the Larger Supplementary Angle is 12 Degrees More Than Three Times the Smaller

To determine the measures of two supplementary angles where the larger angle is 12 degrees more than three times the smaller, set up a system of equations for substitution. Let xx represent the smaller angle and yy the larger. The supplementary definition gives the first equation: x+y=180x + y = 180. The problem's stated relationship translates to y=3x+12y = 3x + 12. Substitute the expression for yy into the first equation to create x+(3x+12)=180x + (3x + 12) = 180. After combining terms to 4x+12=1804x + 12 = 180, subtract 12 to get 4x=1684x = 168. Dividing by 4 yields x=42x = 42. Substitute this value back to find y=3(42)+12=126+12=138y = 3(42) + 12 = 126 + 12 = 138. The angles measure 42∘42^{\circ} and 138∘138^{\circ}.

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Updated 2026-06-24

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