Originally Posted by

**Unknown008** Hm, let's define variables.

Let x be the number of items A.

Let y be the number of items B.

We know that Price for A = 0.23n (for $\displaystyle n\leq 150$) + 0.18(x - n)

Price for B = 0.15y

Now, total gives:

0.23 n + 0.18(x-n) + 0.15y = 139.5

Second equation:

x = y

Substituting in first equation:

0.23n + 0.18(x - n) + 0.15x = 139.5

Assuming that there is less than 150 items of a, makes x - n = 0 and x = n

0.23x + 0 + 0.15x = 139.5

x = 367

But x should have been less than 150!

So, we know that x is greater than 150, so, n = 150

0.23(150) + 0.18(x - 150) + 0.15x = 139.5

34.5 + 0.18x - 27 + 0.15x = 139.5

0.33x = 132

x = 400

So, y = 400