7 over 12r = 21 how do i work this problem out?
2006-09-06 12:41:01 · 8 answers · asked by Anonymous in Education & Reference ➔ Homework Help
7/12r =21 how do i work this problem out? please b-4 9 pm thanx
2006-09-06 12:43:48 · update #1
If your looking for the vaule of r...it is 36
2006-09-06 12:45:20 · answer #1 · answered by Woody 3 · 0⤊ 2⤋
if it's 7/12r=21, then you would multiply each side by 12r to get rid of the fraction.. giving you 7=252r.. then you just divide 7 by 252.. giving you .0277777 w/repeating seven.. can also be written as 1/36. It checks out.. 7/12(1/36)=21.. 21=21..those who wrote it was 36 must not have checked it.. 36*12=432 then 7/432 doesnt equal 21. Hope this helps
2006-09-06 20:02:59 · answer #2 · answered by Anonymous · 0⤊ 0⤋
7/12r=21
(12/7) 7/12r=21
r=21(12/7) cancel out the 7and the 21 to make 3
r= 3(12) r=36
2006-09-06 20:09:48 · answer #3 · answered by Rebecca C 2 · 0⤊ 0⤋
okay...so first what you need to do is get your variable alone. so you have to divide 7 over 12 with another 7 over 12 and they will cancel out. Obviously you have to do the same thing to the other side. So if you want to divide two fractions one is 7 over 12 and other one is 21 over 1. Then you have to multiply them by cross multiplying. So when you multiply 21 into 12 you get 252. 7 into 1 is obviously 7. Then you divide them both. Which will be 252 over 7 and the answer is 36.
R=36
if you don't believe me you can check your answer!
2006-09-06 19:56:00 · answer #4 · answered by premedsophie 3 · 0⤊ 0⤋
You need to multiply both sides of the equation by the reciprocal of 7/12. The reciprocal just means to flip the fraction over. So r will equal whatever 21 times 12/7 is.
Hope this helps.
2006-09-06 19:56:08 · answer #5 · answered by SmileyGirl 4 · 0⤊ 0⤋
multiply both sides by 12r
gives 7=21*12r
divide both sides by 21
gives 7/21=12r
divide both sides by 12
gives (7/21)/12=r
i don't have a calculator handy. hope this helps.
2006-09-06 19:46:04 · answer #6 · answered by gazongas 2 · 0⤊ 1⤋
7 over 12r = 21
X's 12 so that it gets rid of denominater
7r = 252
7 / 252
r = 36
hope that helps :)
2006-09-06 19:47:25 · answer #7 · answered by Confused 2 · 0⤊ 2⤋
hmm looks to me thats not your sons question seems its yours what a pitiful atemt to make ppl do ya home work and still why dont u let "your son" do his work i know how to do it but for this stupid thing youve done u suck
by the way im on 8th grade 2
2006-09-06 19:44:52 · answer #8 · answered by <º)))ß@Ð @š§ @††‡†µÐ€(((º> 2 · 1⤊ 1⤋