30% of the fruits at a fruit stall are apples. 25% of them are peaches and 35% of them are oranges. The remaining 90 fruits
are mangoes. How many fruits are there at the fruit stall?
fruits

You are standing next to a really big circular lake. you want to measure the diameter of the lake, but you don't want to have to swim across with a measuring tape! you decide to walk around the perimeter of the lake and measure its circumference, and find that it's 400\pi\text{ m}400? m. what is the diameter dd of the lake?

I’m confused on how to work the pie charts

The sum of the speeds of two trains is 720.2 mph. if the speed of the first train is 7.8 mph faster than the second train, find the speeds of each.