|
OK, here's how you do it:
Look at the problem. You know that the shop sold T-Shirts and Shorts. You get that just by looking at the words.
But you don't know how many were sold. So they are variables. Call them T (for the number of T-Shirts sold) and S (for the number of shorts sold).
T-Shirts cost $9 so the total money taken in from T-Shirt sales is $9 x T.
Shorts cost $14 so the total amount of money taken in from Shorts sales is $14 x S.
The total money taken in was $256, and this has to equal the total taken in T-Shirts plus the total taken in Shorts, so we have:
($9 x T) + ($14 x S) = $256
Now this has two unknowns so we can't solve it just yet. Instead, we need to look at the word problem for additional information... And there it is: That the store sold twice as many T-Shirts as Shorts. In equations, this is:
T = 2 x S
Now there are two equations in two unknowns, so you just solve. You can plug the value for T from the second equation into the spot where T is in the first:
($9 x 2 x S) + ($14 x S) = $256
simplify:
($9 x 2 + $14) x S = $256
S = $256 / ($9 x 2 + $14)
= $256 / ($18 + $14)
= $256 / $32
= 8
So the number of shorts sold was 8.
Now we can use the second equation to get the value for T.
T = 2 x S
= 2 x 8
= 16
So the number of T-shirts sold was 16.
|