(6.9x0.125x1.75)÷(2.3x1/8x1/4)
=(6.9x1/8x7/4)÷(2.3x1/8x1/4)
=(6.9÷2.3)x(1/8÷1/8)x(7/4÷1/4)
=3x1x7
=21