$1,200, 3.9%, 8months

$1231

Step-by-step explanation:

Given,

Principal amount = $1200

Rate of interest = 3.9%

Time = 8 months or (8/12) 0.666667 years

Formula of simple interest =

A = 1200(1+(0.039 × 0.666667))

A = 1200 (1+0.026)

A = 1200 (1.026)

A = $1231

mr. flanders’ class sold 47 doughnuts and   mr. rodriquez’s class sold 38 cartons of milk

step-by-step explanation:

let x be the number of doughnuts sold by mr. flanders’ class and y be the number of cartons sold by mr. rodriquez’s class.

1. together, the classes sold 85 items, then

x+y=85.

2. both classes earn earned $104.49 for their school. if doughnuts were sold for $1.35 each, then x doughnuts costed $1.35x. if cartons of milk were sold for $1.08 each, then y cartons costed $1.08y. hence,

1.35x+1.08y=104.49.

3. solve the system of two equations:

both equations and proportions are better.