What is the HCF of 27 and 15

Can someone check if i did this correct. it’s number 4 if you’re wondering.

Sherrie is baking a pie for her family. she leaves the room and comes back to 35% of the pie having been eaten before she can put the topping on. how much 1 square inch strips of dough will she need for the top, now that a portion is missing? round your answer to the nearest while nimber.

The length of the line segment ac is 8x-9 what is the value of x