(x + 10) + x : x + 10 = 21 : 18
you're supposed to find x... :|
2006-11-25 23:09:23 · 3 answers · asked by Micah 1 in Science & Mathematics ➔ Mathematics
A ratio is equivalent to a fraction. When two ratios are equal, then it is known as a proportion. Solving ratios require this method of cross-mutilplication.
(x + 10) + x : x + 10 = 21 : 18
(x + 10) + x / x + 10 = 21 / 18 (/ = divide)
Note: write the above on paper in fraction form and you should see better
reduce 21:18 to the lowest factor by dividing by 3 which will be 7 : 6 .Then cross-multiply the two set of fractions.
7(x + 10) = 6 (x + 10 + x)
7x + 70 = 6x + 60 + 6x
7x - 6x - 6x = 60 - 70
-5x = -10
x = 2
2006-11-25 23:45:52 · answer #1 · answered by reut 4 · 0⤊ 0⤋
Use proportions
1. Distribute the brackets: x+10+x:x+10=21:18
2. Add the x: 2x+10:x=21:18
3. Turn into fractions: 2x+10/x=21/18
4. Use proportions: 2x+10*18=21x
5. Solve the equation: 2x+180=21x
180=19x
x= 180/19
Now you can solve this!
2006-11-26 08:59:15 · answer #2 · answered by cutepuppy 1 · 0⤊ 0⤋
ratios are equivalent to fractions
therefore:
21:18 = 7/6
(x+10)+x : x+10 = ((x+10)+ x) / (x+10) = 7/6
6((x+10) + x) = 7(x+10)
6x+60+6x = 7x+ 70
60 - 70 = 7x - 6x - 6x
-10 = -5x
-2 = -x
=> x =2
2006-11-26 11:15:07 · answer #3 · answered by michaell 6 · 0⤊ 0⤋