- Banking To avoid a service fee, y our checking a ccount balance m u st be at least
$500 at th e en d of each m o nth. Your cu rren t b alan ce is $536.45. You use your debit
card to sp en d $125.19. W hat possible a m o u n ts can you deposit into your account
by the en d of the m o n th to avoid paying th e service fee?
Ch al l en g e Reaso n i n g Decide whether each inequality is true for all real numbers. If the
inequality is not true, give a counterexample.
- x + y > x — y 77. If x ^ y, then x + w ^ y + w.
- If w < z, then x~ w> x - z. 79. Ifx>y, thenx>y+w.
- Reasoning Find real n u m b ers a, b, c, and d for w hich it is tru e th a t a < b and
c < d, b u t it is n o t true th a t a — c < b - d.
Apply What You've Learned MATHEMATICALPRA CTICES
MP4
Look back at the inform ation on page 163 ab o u t th e athletic b o o sters’
concession stand.a. Write an inequality th a t relates th e n u m b e r of em pty boxes th e boosters n e e d to
buy for the next game, the n u m b e r of em pty boxes on h and, an d the m axim um
n u m b e r of boxes of po p co rn th e boosters expect to sell.
b. Solve your inequality from p a rt (a). How can you in terp re t your result in the context
of the situation?c. The table from page 163 is show n again below. W hich packages of em pty boxes
can th e athletic boosters buy in o rder to have enough for th e next gam e? (C onsider
th at they m ight buy m ore th a n one package of em pty boxes. Also n o te th a t once
the boosters have enough em pty boxes, they do n o t n e e d to buy any additional
packages.)Em p t y Popcorn Boxes
r
Number of Boxes per Package Price per Box
75 $.25
200 $.21
300 $.19
400Po w erAlg eb ra.com Lesso n 3- 2 So lving In eq u alit ies Using Ad d it io n o r Sub t ract io n 1 7 7