Posted by connie on Thursday, March 15, 2012 at 8:40am.
if i have 550 students and there are 144 more boys than girls how many girls are in class
Connie, I answered this question for you on Tuesday
http://www.jiskha.com/display.cgi?id=1331674038
REINY, Thank you for your answer and the answer is obviously correct when you go back and do the multiplying ......however , I do not just want the answer, I desperately wish to understand from start to finish how you got the answer. I am sorry if I seem stupid, really , but how did you get 2x = 18 , x=9 where did the 18 come from? I am so confused. Thanks for your help!!!! connie
I thought I showed every step in the solution ....
line them up above each other:
2y + 7x = 95
2y + 5x = 77
now subtract them to get
0 + 2x = 18
(2y-2y=0 , 7x-5x = 2x, 95-77 = 18)
so 2x = 18
divide both sides by 2
2x/2 = 18/2
x = 9
sub that back into one of the original equations
2y + 5(9) = 77
2y + 45 = 77
subtract 45 from both sides
2y + 45 - 45 = 77 - 45
2y = 32
divide by 2
y = 16
so x = 9 and y = 16
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