7,5 * 2 целых 31/40: 16,65+0,25

1) 7,5*2³¹/₄₀=75/10*111/40=75*40 / (111*10) = 3000/1110=300/111.

2) 300/111:16,65=300/111:1665/100=300*100 / (111*1665) = 30000/184815=

6000/36963=2000/12321

3) 2000/12321+0,25 = 2000/12321+1/4 = (2000*4+1*12321) / (12321*4) = 20321/49284.