Exercice 17 :
on nomme x le nombre recherché dans chacun des cas.
a. 5.7/x = 1.9/4
a. x = (5.7*4)/ 1.9
a. x = 22.8 /1.9
a. x = 12
b. 0.82/1.3 = 0.41/x
b. x =(1.3*0.41)/0.82
b. x =0.533 / 0.82
b. x = 0.65
c. 7.5/20 = 15/x
c. x = (20*15) / 7.5
c. x = 300 /7.5
c. x = 40
d. 4.05/6.3 = x/0.7
d. x = (4.05* 0.7)/6.3
d. x = 2.835 /6.3
d. x = 0.45
Exercice 20 :
a. 24/75 = (3*2*2*2) / ( 5*5*3) = 8/25
b. 72/18 = (2*4*3*3) / (3*3*2) = 4/1=4
c. 100/56 = (5*2*5*2) / (7*4*2) = 50/28 = (5*2*5) / ( 2*14) = 25/14
d. 36/54 = (6*3*2) / (6*3*3) = 2/3
