5.4×0.68+3.4×2×0.46
＝5.4x0.68+6.8x0.46
=5.4x0.68+0.68x4.6
=(5.4+4.6)x0.68
=10x0.68
=6.8
23.9—0.6×0.6-0.64
=23.9-(0.36+0.64)
=23.9-1
=22.9
13÷12.5
=(13x8)÷(12.5x8)
=104÷100
=1.04
7.8×4.86÷3.9
=4.6x7.8÷3.9
=4.6x2
=9.2