Let's solve this combined operations problem step by step. Martina wants to buy school supplies. She needs 3 notebooks at 10 soles each, 2 pens at 5 soles each, and 1 ruler for 8 soles. Her mother gives her a 10 soles discount for buying everything together.
Now let's calculate step by step. First, we need to find the cost of the notebooks. Martina buys 3 notebooks, and each notebook costs 10 soles. So we multiply 3 times 10, which equals 30 soles for all the notebooks.
Now let's calculate the cost of the pens and ruler. For the pens, we have 2 pens at 5 soles each, so 2 times 5 equals 10 soles. The ruler costs 8 soles. Now we add all the costs together: 30 soles for notebooks, plus 10 soles for pens, plus 8 soles for the ruler, which gives us 48 soles total before the discount.
Finally, we apply the discount. Martina's total before discount was 48 soles. Her mother gives her a 10 soles discount for buying everything together. So we subtract 10 from 48, which gives us 38 soles. Therefore, Martina will pay 38 soles in total for all her school supplies.