Question

an artist makes three types of ceramic statues at a monthly cost of $650 for 180 statues. The manufacturing costs for the three types are $5,$4, and $3. If the statues sell for $20,$12, and $9,respectively, how many of each type should be made to produce $2,100 in monthly revenue?

Answer 1

we have three unknowns and so need three equations

for costs  

x+y+z=180

5x+4y+3z=650

for revenue

20x+12y+9z=2100

x+y+z=180

5x+4y+3z=650

x=30

y=50

z=100