x-1/2=2/5 4/7x=9/14 équations

x - 1/2 = 2/5
10/10x - 5/10 = 4/10
x - 5 = 4
x = 4 + 5
x = 9

4/7x = 9/14
8/14x = 9/14
8x = 9
x = 9/8

Pour la première, je trouve :
X=2/5 + 1/2
= 4/10 + 5/10
= 9/10