If a plant cell in G1 phase with 12 chromosomes undergoes mitosis, how many chromosomes would a daughter cell have

I have my notes here about cell division which could hep you solve the problem on your own.

The first period of the first phase (interphase) of the cell cycle is G1, followed by S and G2, and finally by the mitotic phase.

During G1, the ploidy (the quantity of DNA molecules in the cell) can be represented by the formula 2n (n is the number of DNA molecules in a gamete cell of a given species). During S, DNA duplicates and the quantity of genetic material increases from 2n to 4n. During G2, the quantity remains the same: 4n. After the mitotic phase, the quantity of genetic material decreases to 2n in each daughter cell.