Question for math class

Question

Cara bought 3 lbs. of peanut M&Ms for 0.90 per pound. How many pounds of marshmallow fluff, costing $1.25 per pound, will she need to by so that the cost for her peanut M&M/marshmallow fluff mixture is $1.00 per pound.

Thank you!

Answer 1

3(.9) = x(1.25) = (3+x)1

.27 + 1.25x = 3+x

.25x =.3

x= 4(.3) = 1.2 pounds of $1.25 fluff needed to get $1 mixture

1.25 is within .25 of 1

.9 is within .1 of 1

.25 is 2.5 times further away from 1 than .1 is

2.5 times 1.2 = 3