4th grade math problem

Question

how to solve mathematical question-there are 20 flowers in a vase. 2/5 are roses, 1/4 are daisies, 1/10 are tulips, and the rest are lilies. how many of each type of flower is in the vase?

Answer 1

If 2/5'ths are roses, you can multiply 20 by 2/5 to find the number of roses. A fraction is nothing more than an uncompleted division operation (2/5 is "2 divided by 5" but that division is not yet carried out):

number of roses: 20*(2/5) = 8 (on your calculator: 20 then * then 2 then ÷ then 5 then = )

Similarly for daisies and tulips:

number of daisies: 20*(1/4) = 5

number of tulips: 20*(1/10) = 2

The number of lilies plus the total of the number of other flower types is 20. If we subtract that total from 20 we'll get the number of lilies:

number of lilies: 20 - (8+5+2) = 20 - (15) = 5

That last line comes from this process (n=unknown number of lilies, and 15 is the number of other flower types):

n + 15 = 20

so

n + 15 - 15 = 20 - 15

and

n + 0 = 5

or we can just write

n = 5 (when you get to Algebra, you will learn to do these steps more or less in your head).

Notice how the sum of all four flower types is 8+5+2+5 = 20, as a check.