Answer:
She spent 17 books
Equation: 45+6 = 51 and 51/3 = 17 books
I think its 80 m3 or either 18 m3
Expand the equation.
Multiply (distribute) the first numbers of each set, outer numbers of each set, inner numbers of each set, and the last numbers of each set.
Combine like terms.
Solve the equation and simplify, if needed.