Question 102515
Try this:
Let Tm = Tom's present age and Td = Todd's present age.
From the problem description you can write:
1) Tm = 3*Td "Tom is 3 times as old as Todd"
2) Tm + 4 = 2(Td+4)+6 "In 4 years Tom's age will be 6 years more than 2 times as old as Todd".
Substitute Tm = 3*Td from equation 1) into equation 2) and solve for Td.
2a) 3*Td +4 = 2(Td+4)+6 Simplify.
3Td+4 = 2Td+8+6
3Td+4 = 2Td+14 Subtract 2Td from both sides.
Td+4 = 14 Subtract 4 from both sides.
Td = 10 This is Todd's present age.