-12+8x+2x=2x-8
10x-12=2x-8
8x=4
x=1/2
C
3 yrs ago:
Alice - x
Jane - 3x
Fast forward 2 years... 1 year ago:
Sum of their ages = 62
Equation to solve: x + 3x = 62
4x = 62
----- -----
4 4
x = 15.5
From this, we can deterime that Alice is 15 1/2 years old.
Then, plug in 15.5 for x in 3x to find Jane's age.
15.5 × 3 = 46.5
From this, we can determine that Jane is 46 1/2 years old.
I hope this helps you to understand this problem better.
The ratio is 9 : 7 which means for every 9 pounds of Quartz you have 7 pounds Marble. For the second row Quartz is 72. For the third row it's 11 bags because 99/9 = 11 and 11 times 7 equals 77. The four one is 126 pounds Quartz. Finally the last one is 15 bags and 15 times 7 is 75 pounds of Marble. What you do with the ratio is multiply by the number of bags to figure out with this many bags how many Quartz or Marble. You can do the same thing to figure out how many bags.
Probability of lock code with all even digits = (4/9) ^ 4 = 256/6561 = 0.039
So probabiilty of lock without all even digits = 1 - 0.039 = 0..961.