Hello !
a) a×d + 9×7 = ad + 63
b) 9×m×5×m + k×j×8×j×j×j = 9m × 5m + 8kj × j³
• 9m × 5m + 8kj × j³ = 45m² + 8kj⁴
c) 6n³t - 12nt + 5 - 34tn² + 11 - 45nt
• 6n³t-34tn²-12nt-45nt+5+11
• 6n³t - 34tn² -57nt + 16
d) 67t + 4 -6(t²-2t-8t²+5t)
• 67t + 4 -6t² +12t + 48t² - 35t
• 48t²-6t² + 67t+12t-35t + 4
• 42t² + 44t + 4
Bonne soirée !