What is this answer?

mark drew the following model and said it represented 21÷4 what is 21÷4?

The standard distance between studs in a house is 1.5 feet. if you have a set of blueprints for a house that mark every 1.5 feet with 2 in., by how many inches will a 13-foot wall be represented?

Three times the sum of a number and seven is negative thirty-six. what is the number?

Which fraction is equal to 1hole and 2/5? a.3/5 b.75 c.57 d.73