First, it depends what period you're asking about. Ancient Egyptian mathematics generally refer to pre-hellenistic mathematics, which developed as early as 3500BC, but is better known through a large collection of Papyri from the 12th Dynasty (around 1900BC). After ~350-300BC, Egyptian mathematics was replaced in Egypt by Greek mathematics, which were significantly more advanced, and had essentially modern addition and multiplication.

Ancient Egyptian mathematics did have a concept of division and multiplication (and fractional numbers, generally limited to unit fractions). They could use them to solve algebra problems significantly more complicated than diving a pizza between four people. What ancient Egyptians lacked was long division and long multiplication. (This was common for cultures which did not use a positional system for numbers.)

To multiply numbers, say 9×13, ancient Egyptians would instead decompose one of the two operands into a sum of powers of two (so, in modern notation, 9=1+8=2^0+2^3), then compute the product of the other number with these powers of two through repeated addition (again using modern notation):

13 * 2^0 = 13
13 * 2^1 = 26     (13+13)
13 * 2^2 = 52     (26+26)
13 * 2^3 = 104   (52+52)

Then they would sum the lines corresponding to the base-2 decomposition of the other operand, yielding 13+104=117.

Division was done essentially in the same way, but by computing negative powers of two of the divisor as well.

Of course, it seems fair to speculate that for simpler problems like your example, the solution could be found mentally.

Sources:

• Kline, Morris. Mathematical Thought from Ancient to Modern Times. Vol. 1. Oxford university press, 1990.
• Clagett, Marshall. Ancient Egyptian science: a source book. Vol. 3. American Philosophical Society, 1999.