{ x/3 + 4y/3 = 10
3x - 4y = 100
isolate x for x/3 + 4y/3 = 100
Multiply both sides by 3 :
x/3 3 +4y/3 3 = 100 3
refine : x + 4y = 300
subtract 4y from both sides:
x + 4y - 4y = 300 - 4y
refine : x = 300 - y
subsititute x = 300 - y
[ 3(300 - 4y ) - 4y = 100 ]
900 - 16y - 900 = 100 - 900
- 16 y = - 800
y = - 800 / - 16
y = 50
for x = 300 -y :
subsititute y = 50
x = 300 - 4 50
x = 300 - 200
x = 100
the solutions to the system equations are :
x = 100 , and y = 50
Answer D
hope this helps!
