In school the ratio of the number of pupils to the number of teachers is 20:1 of the number of pupils is 840 how many teachers are there

Sadie computes the perimeter of a rectangle by adding the length, l, and width, w, and doubling this sum. eric computes the perimeter of a rectangle by doubling the length, l, doubling the width, w, and adding the doubled amounts. write an equation for sadie’s way of calculating the