We have an unknown number, say "x" that needs to be solved:
Forming an equation from the sentences gives:
1/3 of a number x = [tex] \frac{x}{3} [/tex]
7 more than a third of a number = 7 + [tex] \frac{x}{3} [/tex]
But this all equals 57, so our equation is
7 + [tex] \frac{x}{3} [/tex] = 57
Therefore, x=150