Algebra Demystified 2nd Ed

(Marvins-Underground-K-12) #1
Chapter 8 linear appliCaTionS 247

PRACTICE


  1. The sum of two numbers is 10. Three times the smaller plus five times
    the larger number is 42. What are the numbers?

  2. The difference between two numbers is 12. Twice the smaller plus four
    times the larger is 108. What are the two numbers?

  3. The difference between two numbers is 8. The sum of one and a half times
    the smaller and four times the larger is 54. What are the numbers?

  4. The sum of two numbers is 11. When twice the larger is subtracted from
    five times the smaller, the difference is 6. What are the numbers?


✔SOLUTIONS



  1. Let x represent the smaller number. The larger number is then 10 − x.
    3510 42
    3505 42
    25042
    50 50
    28


xx
xx
x

x
x

+−=
+−=
−+=
−−
−=−
=

()

−−

=

8
2
x 4
The numbers are 4 and 10 – x = 10 – 4 = 6.


  1. The difference between the numbers is 12, so one number is 12 more
    than the other. Let x represent the smaller number. Then x+ 12 is the
    larger. Twice the smaller is 2x, and four times the larger is 4(x + 12).


2412 108
2448 108
648 108
48 48
660

xx
xx
x

x
x

++=
++=
+=
−−
=

()

==
=

60
6
x 10
The smaller number is 10 and the larger is x + 12 = 10 + 12 = 22.


  1. The difference between the numbers is 8, so one of the numbers is 8
    more than the other. Let x represent smaller number. The larger number


PRACTICE


  1. The sum of two numbers is 10. Three times the smaller plus five times

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