Question 169126
x + y = 20 multiply by -16 & add.
28x + 16y = 416
-16x-16y=-320
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12x=96
x=96/12
x=8 ans.
8+y=20
y=20-8
y=12 ans.
Proof:
28*8+16*12=416
224+192=416
416=416