Why my answer is incorrect? explain plezz

Afarmer has decided to divide his land area in half in order to plant soy and corn. calculate the area of the entire area so he knows how much soil is needed. each bag of soil covers 20 square yards. how many bags should the farmer purchase? (4 points) 1 bag 2 bags 3 bags 4 bags

Mrs. blake's bill at a restaurant is $42.75. she wants to leave the waiter an 18% tip. how much will she pay in all, including the tip?

Can someone show me step by step how to do this?