WAEC Mathematics 2018 Paper

m + n = 110$^{\circ}$, (n + r) = 130$^{\circ}$

(m + n) = 120$^{\circ}$

then, r = 130$^{\circ}$ - n

and;

m + (130^o - n) = 120$^{\circ}$

m - n = -10$^{\circ}$

2m + (n + r) = 110 + 120 = 230

2m + 130 = 230

2m = 230 - 130

m = $\;\frac{100}{2}$ = 50$^{\circ}$

n = 110$^{\circ}$ - 50$^{\circ}$

= 60$^{\circ}$

r = 130$^{\circ}$ - 60$^{\circ}$ = 70$^{\circ}$

Hence, the ratio m : n : r

= 50 : 60 : 70

= 5 : 6 : 7