Cupro-nickel coins are minted by mixing copper and nichel in the ratio 4:1

a) How much copper is needed to mix with 20kg of nickel?

b) How much nickel is needed to mix with 20kg of copper?

Copper: Nickel = 4:1

a) How much copper needed for 20 kg nickel

C:N = 4: 1

C:20 = 4:1

C/20 = 4/1 Cross Multiply

C*1 = 4*20

C = 80

80kg Copper would be needed.

b) How much Nickel would be needed for 20 kg of Copper

C:N = 4: 1

20:N = 4:1

20/N = 4/1 Cross Multiply

4*N = 1*20

4N = 20 Divide both sides by N.

N = 20/4 = 5

5kg Nickel would be needed.