По действиям
1.69/70 * 7/23 = 69*7/70*23 = 483/1610 = 3*161/10*161 = 3/10 = 0.3
2.4/25 ÷ 4/25 = 4/25 × 25/4 = 4·25/25·4 = 100/100 = 1
3.3/5 × 25/36 = 3·25/5·36 = 75/180=75/180 = 5·15/12·15 = 5/12
4.3/10 - 10/10 = 3 - 10/10 = -7/10
5.-7/10 + 5/12 = 5/12 - (-7/10) = 5·5/12·5 - -7·6/10·6 = 25/60 - -42/60 = 25 - 42/60 = -17/60