Identify the steeper line x+10 y=1 or 3 x+20 y=1

Amerchant has coffee worth $60 a pound that she wishes to mix with 50 pounds of coffee worth $90 a pound to get a mixture that she will sell for $70 a pound. how many pounds of the & 60 coffee should be used?

Ben is three times as old as samantha, who is two years older than half of michel's age. if michel is 12. how old is ben?

Nine more than four times a number is the same as one less than twice the number. find the number?