Answer:
75 pounds of fudge & 80 pounds of toffee per month.
Explanation:
Let qty of fudge be x pounds & qty of toffee be y pounds per month
They make an average of 155 pounds of fudge and toffee combined each month
x+y=155 (1)
They sell a pound of fudge for $8.40 and a pound of toffee for $7.28. Mandy's averages $1,212.40 each month in fudge and toffee sales.
So the cost of monthly fudge&toffee is 8.40*x+7.28*y=1,212.40
8.40x+7.28y=1212.40 ;(2)
multiply eq (1) by 8.40 & then subtract 2 from 1
8.40x+8.40y=155*8.40
8.40x+8.40y=1,302 (1')
8.40x+7.28y=1212.40 ;(2)
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(8.40-7.28)y=1,302-1,212.40
1.12y=89.60
y=89.60/1.12=80 pounds of toffee
In order to solve for x, take the value for y and substitute it back into either one of the original equations.
x+80=155
x=155-80=75 pounds
So they make 75 pounds of fudge & 80 pounds of toffee per month.