Question 20

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waecmaths question: 

In the diagram, PQR is straight line (m + n) = 120o and (n + r) = 100o. Find (m +r)

Option A: 

110o

Option B: 

120o

Option C: 

140o

Option D: 

160o

waecmaths solution: 

$\begin{align}  & m+n+r={{180}^{\circ }} \\ & r={{180}^{\circ }}-(m+n)={{180}^{\circ }}-{{120}^{\circ }}={{60}^{\circ }} \\ & n+r={{100}^{\circ }} \\ & n+{{60}^{\circ }}={{100}^{\circ }} \\ & n={{40}^{\circ }} \\ & m+n={{120}^{\circ }} \\ & m+{{40}^{\circ }}={{120}^{\circ }} \\ & m={{80}^{\circ }} \\ & m+r={{80}^{\circ }}+{{60}^{\circ }}={{140}^{\circ }} \\\end{align}$

maths year: