Solve the system of equations using substitution 4x+y=23 y=x+8

What situation is an example of an observational study

Problem melissa is her dad build a walkway in their backyard. the walkway will be 54 feet long and 1.5 feet wide. the local hardware store sells tiles which are 1.5 by 1.5 feet and come in boxes of 12. how many boxes of tiles do they need?

Solve this system of equations. 12x − 18y = 27 4x − 6y = 10