（9x+59-5x)\3=29
9x+59-5x=29×3
9x-5x=87-59
4x=28
x=28÷4
x=7
6.4-2(x+ 1.2）=0.4
2(x+1.2)=6.4-0.4
2(x+1.2)=6
x+1.2=6÷2
x+1.2=3
x=1.8