Răspuns:
a. a×b×c×d= 12×30=360
b. 7ac-2bd=7×12-2×30= 84-60=24
c. 15ac:2bd=15×12:2×30=180:2×30=90×30=270
a·c = 12
b·d =30
a) a·b·c·d = 12 · 30 = 360
b) 7ac - 2bd = 7 · 12 - 2 · 30
= 84 - 60
= 24
c) 15ac : 2bd = (15 · 12) : (2 · 30)
= 180 : 60
= 3
