SOLUTION: Write an equation or a system of equations that can be used to solve each of the following problems. In each case, state what the variable or variables represent.(solution of the e

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Question 197531: Write an equation or a system of equations that can be used to solve each of the following problems. In each case, state what the variable or variables represent.(solution of the equations is not required.)
a) Julie can keypunch a certain number of computer cards in 4 hours. It takes Pat 6 hours to keypunch the same number of computer cards. If Julie and pat work together, how long will it take them to keypunch that number of cards?
b) The sum of the digits of a two-digit number is 7. If the digits are reversed, the new number is two more than twice the original number. Find the original number.
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
Write an equation or a system of equations that can be used to solve each
of the following problems. In each case, state what the variable or
variables represent.(solution of the equations is not required.)
:
a) Julie can keypunch a certain number of computer cards in 4 hours.
It takes Pat 6 hours to keypunch the same number of computer cards.
If Julie and pat work together, how long will it take them to keypunch that number of cards?
;
Let t = no. of hrs required when working together
Let the completed job = 1
t%2F4 + t%2F6 = 1
:
:
b) The sum of the digits of a two-digit number is 7. If the digits are
reversed, the new number is two more than twice the original number.
Find the original number.
:
Two digits; x and y: The number = 10x + y
"sum of the digits of a two-digit number is 7."
x + y = 7
y = (7-x); use for substitution
:
"If the digits are reversed, the new number is two more than twice the original number.
10y + x = 2(10x + y) + 2
10y + x = 20x + 2y + 2
10y - 2y = 20x - x + 2
8y = 19x + 2