Question 1110164: Janet is three years younger than Rebecca. Eight years ago, Janet was half Rebecca's age. How old is each girl now? Answer by ikleyn(52786) (Show Source):
J = R - 3 (1) ("Janet is three years younger than Rebecca.".)
J-8 = 0.5*(R-8) (2) ("8 years ago . . . ")
Substitute eq(1) into eq(2). You will get
(R-3) - 8 = 0.5*(R-8)
R-11 = 0.5*(R-8)
Multiply it by 2 (both sides)
2R - 22 = R - 8
2R - R = 22 - 8 = 14 ====> R = 14.
Answer. Rebecca is 14 years old. Janet is R-3 = 14-3 = 11 years old.
