# 925 USD

Four classmates saved an annual total of 925 USD. The second save twice as the first, the third 35 USD more than the second, and the fourth 10 USD less than the first. How does USD save each of them?

a =  150
b =  300
c =  335
d =  140

### Step-by-step explanation:

a+b+c+d=925
b=2a
c = 35+b
d = a-10

a+b+c+d=925
b=2·a
c = 35+b
d = a-10

a+b+c+d = 925
2a-b = 0
b-c = -35
a-d = 10

Pivot: Row 1 ↔ Row 2
2a-b = 0
a+b+c+d = 925
b-c = -35
a-d = 10

Row 2 - 1/2 · Row 1 → Row 2
2a-b = 0
1.5b+c+d = 925
b-c = -35
a-d = 10

Row 4 - 1/2 · Row 1 → Row 4
2a-b = 0
1.5b+c+d = 925
b-c = -35
0.5b-d = 10

Row 3 - 1/1.5 · Row 2 → Row 3
2a-b = 0
1.5b+c+d = 925
-1.6667c-0.6667d = -651.6667
0.5b-d = 10

Row 4 - 0.5/1.5 · Row 2 → Row 4
2a-b = 0
1.5b+c+d = 925
-1.6667c-0.6667d = -651.6667
-0.3333c-1.3333d = -298.3333

Row 4 - -0.33333333/-1.66666667 · Row 3 → Row 4
2a-b = 0
1.5b+c+d = 925
-1.6667c-0.6667d = -651.6667
-1.2d = -168

d = -168/-1.2 = 140
c = -651.66666667+0.66666666666667d/-1.66666667 = -651.66666667+0.66666667 · 140/-1.66666667 = 335
b = 925-c-d/1.5 = 925-335-140/1.5 = 300
a = 0+b/2 = 0+300/2 = 150

a = 150
b = 300
c = 335
d = 140

Our linear equations calculator calculates it. Did you find an error or inaccuracy? Feel free to write us. Thank you!

Tips for related online calculators
Do you have a system of equations and looking for calculator system of linear equations?