1條數學題

Let the smaller number be A.
Let the larger number be B.
Now, the difference between the two numbers is 10, we have
B – A = 10
A = B - 10 -----(i)
If the sum of the smaller number mupltiplied by 4 and the larger number multiplied by 1/3 is 25, we have
4A + 1/3B = 25 -----(ii)
Substitute (i) into (ii), we have
4(B – 10) + 1/3B = 25
4B – 40 + 1/3B = 25
4B + 1/3B = 25 + 40
13/3B = 65
B = 65 x 3/13
= 15 -----(iii)
Substitute (iii) into (i), we have
A = 15 – 10
= 5
Therefore, the smaller number is 5, and the larger number is 15.

4n + (n+10)*(1/3) = 25
4n*3 + n + 10 = 3*25
12n + n = 75 - 10
13n = 65
n = 5

So the 2 numbers are 5 and 15 (5+10)

Let x be the smaller number,
(x+10) is1 the larger number,

4x+ 1/3 (x+10) = 25
12x + x+ 10 = 75 [乘3]
13x = 65
x=5

The smaller number is 5
The larger number is (5+10)=15

let the two number be x and y
x-y=10---------------------------------1
1/3x+4y=25------------------------------------2

in (1),
x=10+y------------------------------------3

put (3) into (1),
1/3(10+y)+4y=25
(10+y)+12y=25*3
10+13y=75
13y=65
y=5

put y=5 into (3)
x=y+10
x=5+10
x=15

so, x=15, y=5

Let the smaller number be n
The larger number is n+10

Now the sum
4n + (n+10)*(1/3) = 25
4n*3 + n + 10 = 3*25
12n + n = 75 - 10
13n = 65
n = 5

So the 2 numbers are 5 and 15 (5+10)