Mary are one of the muffins she baked and had 12 left. write an equation to find how many muffins mary started with.

Me because some of question i don’t understand

Suppose that sahil knows that 45 people with ages of 18 to 29 voted. without using a calculator, he quickly says then 135 people with ages of 30to 49 voted. is he correct? how might sohil have come up with his answer so quickly?

In the sixth grade 13 out of 20 students have a dog if there are 152 sixth grade students how many of them have a dog