math word problem please help me solve and understand..?

Question

A certain recipe calls for 2 cups of milk for every 3 cups of flour. If 2 cups of flour are used, how many cups of milk should be used?

and also,

an ear of corn cost 20 cents last year and 30 cents this year. by what percent has the price increased?

thanks....

Answer 1

set up a porportion:

(2 cups milk) / (3 cups flour) = (x cups milk) / (2 cups flour)

2/3 = x/2
x = 4/3 cups of milk

and also,

it increased by 10 cents, from 20 cents to 30 cents.
so 10 is what percent of 20, that will tell you the answer:

100*(10/20) = %50 increase

Answer 2

for every 3 cups of flour --------------2 cups milk nedded

for each cup of floor -----------------(2/3) cups of milk needed

so for 2 cups of floor ----------------(2/3)*2 = 4/3 cups of milk nedded

b)

increase in cost of corn = 30 - 20 = 10 cents

the increse for 20 cents = 10 cents

the increse for 100 cents = (10/20)*100 = 50%

Answer 3

If you are using 2/3rds as much flour, you would need to use 2/3rds as much milk. 2 cups of milk = 6/3rds. 2/3rds of 6/3rds = 4/3rds. 4/3rds = 1 1/3rds cup of milk.

30 divided by 20 = 1.5 or 150%. It hasn't increased 150% because it was already 100%, so it has increased 50%.

Answer 4

1) Let M = number of cups of milk
Let F = number of cups of flour

M / 2 = F / 3
3M = 2F
3M = 2(2)
3M = 4
M = 4/3 cups

Therefore 4/3 cups of milk should be used.

2)
20 * (1 + increase) = 30
20 + 20(increase) = 30
20(increase) = 10
increase = 0.5

Therefore the price of corn increased by 50%