In ∆DEF, if m∠E is one more than three times m∠F and m∠D is three more than seven times m∠F, find the m∠D.

Answer: mD=115, mE=49, mF=16
Step-by-step explanation:
DEF is a triangle and were told to find angle measures.
If m∠E is (3F+1) and m∠D is (7F+3)
Use T-angle sum theorem and plug previous terms 7F+3+3F+1+F=180 which give F=16. Then substitute F=16 with angles D and E to find last results.
The measure of m∠D is 115 degrees
In the given triangle ∆DEF, if m∠E is one more than three times m∠F, hence;
m∠E = 3m∠F + 1
Similarly, if m∠D is three more than seven times m∠F, then;
m∠D = 7m∠F + 3
Taking the sum of the angles and equate it to 180 degrees
m∠D + m∠E + m∠F = 180
7m∠F + 3 + 3m∠F + 1 + m∠F = 180
11m∠F + 4 = 180
11m∠F = 180-4
11m∠F = 176
m∠F = 16
Since m∠D = 7m∠F + 3
m∠D = 7(16) + 3
m∠D = 115 degrees
Hence the measure of m∠D is 115 degrees
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