jika a=1/2,b=-2/3,dan c=4/5,tentukan: a.2b-5ac b.3c(5a-4b) c.6a:4bc

a. 2b-5ac
= 2×(-2/3) - 5×1/2×4/5
= -4/3 - 20/10
= -4/3 - 2/1
= -4/3 - 6/3
= -10/3
= -3 1/3

b. 3c(5a-4b)
= 3×4/5(5×1/2 - 4(-2/3))
=12/5(5/2 + 8/3)
=12/5(15/6 + 16/6)
= 12/5(31/6)
= 12/5 × 31/6
= 372 × 30
= 12 12/30
= 12 2/5

c. 6a ÷ 4bc
= 6×1/2 ÷ 4×(-2/3)×4/5
= 6/2 ÷ (-32/15)
= 6/2 × (-15/32)
= -90/64
= - 45/32