Need some math help

To solve it, assume that the first three - symbols are dashes, not subtraction signs, because she is trying to generate a telephone number.

The cube root of 54,872,000 is 380. 

That gives 1-650-380-....  

In the last figure, the parenthesized number would be:

7/10*(9-(11i)^2) =
7/10*(9-(11^2*i^2) =
And since i^2 = -1, the rest follows:
7/10*(9+11^2) =
7/10*130 = 91

but since four digits are required, I'd write it as 0091

So Paula's number is 1-650-380-0091