B. 1.67 x 10^-24g
Hope this helps?
X*80+y*60= 50*74
x +y =50 | * ( -60)
80x + 60y= 50*74
-60x - 60y=-50*60
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20x= 50*(74-60)=50*14
x=50*14/20=35 pounds of 80 cents tea
y=50-35=15 pounds of 60 cents tea
The ordered pairs are probably (0,10) and then (-1,5).