Please help me, I need an explanation as well please, not just the answer

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?

Ageologist had two rocks on a scale that weighed 4.6 kilograms together.rock a was 0.5 of the total weight.how much did rock a weigh?

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