RomainVTT Bonjour,
pour additionner ou soustraire des fractions il faut qu'elles aient le même dénominateur
a) 3 + 2/10 = > (3x10)/(1x10)+2/10 = 30/10 +2/10 = (30+2)/10 = 32/10 = 3.2

b) 75 +1/10 + 9/100 = (75x100)/(1x100) + (1x10)/(10x10) + 9/100 = 7500/100 + 10/100 + 9/100 = (7500+10+9)/100 = 7519/100 = 75.19

c) 3/100 + 6/1000 = (3x10)/(100x10) + 6/1000 = 30/1000 + 6/1000 = (30+6)/1000 = 36/1000 = 0.036

d) 9 +4/10 + 3/100 + 7/1000 = (9x1000)/(1x1000) + (4x100)/(10x100) + (3x10)/(100x10) + 7/1000 = 9000/1000 + 400/1000 + 30/1000 + 7/1000 = (9000+400+30+7)/1000 = 9437/1000 = 9.437

e) 258 + 8/10 + 5/1000 = (258x1000)/(1x1000) + (8x100)/(10x100) + 5/1000 = 258000/1000 + 800/1000 + 5/1000 = (258000+800+5)/1000 = 258805/1000 = 258.805

f) 7 +1/10 + 9/10000 = (7x10000)/(1x10000) + (1x1000)/(10x1000) + 9/10000 = 70000/10000 + 1000/10000 + 9/10000 = (70000+1000+9)/10000 = 71009/10000 = 7.1009

noham1189 A. 3,2
b. 75,19
c. 0,036
d. 9,437
e. 258,805
f. 7,1009