Can your daughter post the "banker's rule" ?
It must be explained in her materials.
She needs to substitute the number 3750 for the symbol that represents Future Value.
She needs to substitute the number 418 for the time variable, most likely.
The rate is usually expressed as a decimal. 15% is the same as 0.15. That gets substituted for the corresponding symbol in the formula.
I regret that I do not have the time to duplicate her lessons, here.