 #1
harpazo
 208
 16
 Homework Statement:
 Set up a system of equations to find the ages of Martin and his brother Luther.
 Relevant Equations:

M = 4L
M + 10 = 2(L + 10)
Martin is four times as old as his brother Luther at present. After 10 years he will be twice the age of his brother. Find their present ages.
Let M = Martin
Let L = Luther
Martin is four times as old as his brother Luther at present.
M = 4L
After 10 years he will be twice the age of his brother.
M + 10 = 2(L + 10)
I came up with the following equations:
M = 4L...Equation A
M + 10 = 2(L + 10)...Equation B
I will now replace M in Equation B with 4L.
4L + 10 = 2(L + 10)
4L + 10 = 2L + 20
4L  2L = 20  10
2L = 10
L = 10/2
L = 5
Luther is 5 years old.
Martin is 4 times Luther's age or 4(5) is 20 years old.
Let M = Martin
Let L = Luther
Martin is four times as old as his brother Luther at present.
M = 4L
After 10 years he will be twice the age of his brother.
M + 10 = 2(L + 10)
I came up with the following equations:
M = 4L...Equation A
M + 10 = 2(L + 10)...Equation B
I will now replace M in Equation B with 4L.
4L + 10 = 2(L + 10)
4L + 10 = 2L + 20
4L  2L = 20  10
2L = 10
L = 10/2
L = 5
Luther is 5 years old.
Martin is 4 times Luther's age or 4(5) is 20 years old.