Answer :

[tex]\dfrac{2}{3}x=436\\ x=436\cdot\dfrac{3}{2}\\ x=654[/tex]
2/3 of x=436
'of' can be translated as multiply
2/3 times x=436
multiply both sides by 3/2 to clear fraction (because 3/2 times 2/3=6/6=1)
1x=436 times 3/2
x=654

the number is 654