SOLUTION: 1. The sum of the ages of two friends is 60. if three times the age of one friend is 9 less than four times the age of the other, how old is each?
2. Rolly is twice as old as hi
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2. Rolly is twice as old as hi
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Question 147760: 1. The sum of the ages of two friends is 60. if three times the age of one friend is 9 less than four times the age of the other, how old is each?
2. Rolly is twice as old as his brother, Darwin. In five years, Darwin will be the same age as his brother ten years ago. What are their present ages? Answer by ankor@dixie-net.com(22740) (Show Source):
You can put this solution on YOUR website! 1. The sum of the ages of two friends is 60.
x + y = 60
y = (60-x)
;
three times the age of one friend is 9 less than four times the age of the other,
3x = 4y - 9
:
how old is each?
:
Substitute (60-x) for y in the above equation:
3x = 4(60-x) - 9
3x = 240 - 4x - 9
:
3x + 4x = 240 - 9
:
7x = 231
x =
x = 33 yrs old
then
60 - 33 = 27 yrs old
;
:
Check solution in the statement:
three times the age of one friend is 9 less than four times the age of the other,
3(33) = 4(27) - 9
99 = 108 - 9
:
:
2. Rolly is twice as old as his brother, Darwin.
r = 2d
:
In five years, Darwin will be the same age as his brother ten years ago.
d + 5 = r - 10
d = r - 10 - 5
d = r - 15
:
What are their present ages?
:
Substitute 2d for r in the above equation
d = 2d - 15
d - 2d = -15
-d = -15
d = 15 yrs is Darwin's present age
then
2(15) = 30 yrs is Roll's present age
:
Check solution in statement:
In five years, Darwin will be the same age as his brother ten years ago.
15 + 5 = 30 - 10
