If she sells each of her cake for 3.10 and sold 24 cakes, she made a total of 3.10 x 24 = 74.4 (pounds)
Each cake costs 80p to make, so the cost to make all 24 cakes is 80 x 24 = 1920p, or 19.2 pounds.
So, she made a total of 74.4 - 19.2 = 55.2 pounds of profits.