Anders and Petra and Karin are together 18 years old.Anders is half the age of Karin.Petra is half the age of Anders and Karin's age together.how old are the children?
A + P + K = 18 ...(1)
A = K/2 Multiply both sides by 2 to get 2A = K ...(2)
P = (A + K)/2 ...(3)
Replace K in (1) and (3) using (2)
A + P + 2A = 18 or 3A + P = 18 ...(4)
P = (A + 2A)/2 or P = 3A/2 ...(5)
Replace P in (4) using (5)
3A + 3A/2 = 18 or 9A/2 = 18 so 9A = 36 or A = 4
Use A in (5) to get P = 3*4/2 or P = 6
Use A in (2) to get K = 2*4 or K = 8
Anders is 4, Petra is 6, Karin is 8
A + P + K = 18 ...(1)
A = K/2 Multiply both sides by 2 to get 2A = K ...(2)
P = (A + K)/2 ...(3)
Replace K in (1) and (3) using (2)
A + P + 2A = 18 or 3A + P = 18 ...(4)
P = (A + 2A)/2 or P = 3A/2 ...(5)
Replace P in (4) using (5)
3A + 3A/2 = 18 or 9A/2 = 18 so 9A = 36 or A = 4
Use A in (5) to get P = 3*4/2 or P = 6
Use A in (2) to get K = 2*4 or K = 8
Anders is 4, Petra is 6, Karin is 8