jawab soal matmin Tolong Karna Gak ngerti

a) i) QP + QR
       QR = PS
       QP + QR = QP + PS = QS
    ii) PQ + PS + RS + SQ
        PS = QR
        PQ + PS + RS + SQ = PQ + QR + RS + SQ = PQ
    iii) SO - QO = SO + OQ = SQ
    iv) PR - SR + SQ = PR + RS + SQ = PQ

b) i) SR = PQ = a
    ii) PR = PQ + QR
        QR = PS 
        PR = PQ + QR = PQ + PS = a + b
    iii) SQ = SP + PQ = -PS + PQ = -b + a = a - b

kalo ada yang kurang jelas tanya aja