I'll show you how I do it,hope you'll like it.
5:7, 5+7=12
5/12×48 =20
7/12×48=28
answer=
5:7
= 20:28
hope it helps.....
Let us assume the first number = x
Then the second number = 5x -2
The third number = x + 4
The total number that needs to be divided into three parts is 219
Then we can write the equation as
x + 5x - 2 + x + 4 = 219
7x + 2 = 219
7x = 219 - 2
7x = 217
x = 217/7
= 31
Then
First number = 31
Second number = 5x - 2
= (5 * 31) - 2
= 155 -2
= 153
Third number = x + 4
= 31 + 4
= 35
So the three numbers are 31, 153 and 35.
The value of x is 6
Found using the Angle-Sum-Property of a Triangle
first off, I'd like to point out that for the 5th test, he has 96, and that's +6 above 90, and therefore it should be 6.
if all the above/below numbers, summed up yield 0, that simply means the average is an even 90 on average for all 6 tests, if they yield above 0, is above on the average, and if it's below 0, a negative value, he needs to do more work.
-7+4-11+7+6-3 = -4.
you can think of it this way, if he had 90 on all 6 tests, the above/below row will show 0, 0, 0, 0, 0, 0. If any of the tests was above 90, that row will yield a sum more than 0, and if any of the tests were below, that sum will be a negative value.
