WAEC - Mathematics (1996 - No. 37)

considering SPQ
S = 34^o (base ∠s of Isos. Δ)
P = 180^o - 68^o = 112^o
R = 122/2 = 56^o
a = 34^o (alt ∠s)
SQR = 180^o - (56 + 34)
180^o - 90^o = 90^o