40-120%x=10
40-1.2x=10
40-10=1.2x
30=1.2x
x=30÷1.2
x=25
1/2+2/3x=11/12
2/3x=11/12-1/2
2/3x=5/12
x=(5/12)÷(2/3)
x=5/8