At Westonci.ca, we provide clear, reliable answers to all your questions. Join our vibrant community and get the solutions you need. Discover detailed answers to your questions from a wide network of experts on our comprehensive Q&A platform. Experience the convenience of finding accurate answers to your questions from knowledgeable experts on our platform.

the sum of Marys age and her moms age is 67.  Three times Marys age increased by 7 is her moms age.  How old is Mary and her mother


Sagot :

Ryan2
Sove the system:

x: Mary´s age
y: Mom´s age:

x + y = 67
3x + 7 = y

Replace y in the first equation:

x + 3x + 7 = 67
4x = 67 - 7
4x = 60
x = 15 yrs.

y = 67  - 15 = 52 yrs
AL2006
Labels:
-- Mary's age = D (for 'daughter')
-- Mom's age = M (for 'mom')

The problem says 2 things:

         D + M = 67
and
       3D + 7 = M .

Let's subtract 'M' from each side of the first one:  D = 67 - M

Now we can plug that into the second one, in place of 'D'.
 
       3D          + 7 = M

       3(67 - M) + 7 = M .

Clear the parentheses on the left side.  I assume you know how to do that.

       201 - 3M + 7 = M

Add 3m to each side:

       201        + 7 = 4M

       208              = 4M

Divide each side by 4 :

       52 = Mom's age

Daughter's age = 67 - Mom's age = 67 - 52 = 15