Please Help, GodBless

You put the following items into your rucksack. ham 600 g cheese 380 g tomatoes 270 g how much do all the ingredients weigh in total?

The average human heart beats 1.15 \cdot 10^51.15⋅10 5 1, point, 15, dot, 10, start superscript, 5, end superscript times per day. there are 3.65 \cdot 10^23.65⋅10 2 3, point, 65, dot, 10, start superscript, 2, end superscript days in one year. how many times does the heart beat in one year? write your answer in scientific notation, and round to one decimal place.

School has 204 sixth grade students. if the sixth grade is 30% of the total school, how many students are in the middle school?